Showing 1–50 of 69 results for author: Montalto, M

Assessment of PLATO Science Performance

Authors: Juan Cabrera, Heike Rauer, Reza Samadi, Valerio Nascimbeni, Anko Boerner, Denis Grießbach, Carsten Paproth, Martin Pertenaıs, Sami-M. Niemi, Szilard Csizmadia, Asier Abreu, Conny Aerts, Suzanne Aigrain, Matthias Ammler-von Eiff, Beatriz Aparicio del Moral, Thierry Appourchaux, David J. Armstrong, Ann Baeke, Gabor G. Balazs, Kevin Belkacem, Aaron Birch, Paz Bluhm, Tobias Boenke, Fabrice Boquet, Sam Bowling , et al. (99 additional authors not shown)

Abstract: The PLATO mission is scheduled for launch early 2027. In this paper we present an overview of the performance drivers for the mission at the time where all flight models of the cameras have been tested and integrated on the optical bench. The PLATO consortium needs an estimate of the planet detection yield to dimension the ground-based radial velocity follow-up resources. We provide updated estima… ▽ More The PLATO mission is scheduled for launch early 2027. In this paper we present an overview of the performance drivers for the mission at the time where all flight models of the cameras have been tested and integrated on the optical bench. The PLATO consortium needs an estimate of the planet detection yield to dimension the ground-based radial velocity follow-up resources. We provide updated estimates on the yield of planet detections that can be expected from the mission under certain assumptions. As of today, large uncertainties remain on the planet occurrence rates, especially for small planets in long-period orbits, and on our ability to detect these planets in the presence of stellar variability and instrumental noise. To partially overcome these limitations, we compare results using different planet occurrence rates, detectability rates, and we include an estimate on the expected contribution of stellar variability to the noise budget. The final detection yield of PLATO will provide constraints to planet occurrence rates which in turn will help constraining planet formation models. △ Less

Submitted 6 April, 2026; originally announced April 2026.

Comments: submitted to the special issue on PLATO in Experimental Astronomy

The PLATO Input Catalogue of targets (tPIC) for the first Long Pointing Field

Authors: M. Montalto, G. Piotto, P. M. Marrese, L. Prisinzano, S. Marinoni, V. Granata, J. Cabrera, V. Nascimbeni, S. Desidera, V. Adibekyan, S. Ortolani, E. Alei, C. Aerts, G. Altavilla, K. Belkacem, S. Benatti, A. Börner, M. Deleuil, M. Fabrizio, L. Gizon, M. J. Goupil, M. Günther, A. M. Heras, D. Magrin, L. Malavolta , et al. (8 additional authors not shown)

Abstract: The ESA PLAnetary Transits and Oscillations of stars (PLATO) mission is designed to detect terrestrial planets in the habitable zones of solar-type stars. Owing to telemetry constraints, the selection of PLATO targets must be performed in advance. In this paper, we present the first public release of the PLATO Input Catalogue of targets (tPIC2.2), which provides the list of stars that will be obse… ▽ More The ESA PLAnetary Transits and Oscillations of stars (PLATO) mission is designed to detect terrestrial planets in the habitable zones of solar-type stars. Owing to telemetry constraints, the selection of PLATO targets must be performed in advance. In this paper, we present the first public release of the PLATO Input Catalogue of targets (tPIC2.2), which provides the list of stars that will be observed during the PLATO first Long-duration Observation Phase field at South (LOPS2) as part of its core science program. We exploit astrometric and photometric data from Gaia Data Release 3 (DR3), together with three-dimensional maps of the local interstellar medium, to identify stars belonging to the PLATO stellar samples as from mission requirements. The tPIC comprises 217,741 stars, including 202,315 FGK dwarfs and subgiants, 15,037 M dwarfs and 789 known planet host stars. The median distances of the samples are 512 pc for FGK stars and 133 pc for M dwarfs. We estimate interstellar reddening for almost all targets and develop an algorithm to infer fundamental stellar parameters (effective temperature, radius, and mass) in an homogeneous way from astrometric and photometric observables. The tPIC fulfills all the science requirements of the PLATO mission. The tPIC also includes a list of stars that host known exoplanets (confirmed or still candidate), located within the LOPS2 field. △ Less

Submitted 3 April, 2026; originally announced April 2026.

Comments: 21 pages, 16 tables, 13 figures. Submitted to A&A

The PLATO field selection process III. Selection of the Prime Sample for the LOPS2 field

Authors: V. Nascimbeni, G. Piotto, V. Granata, S. Marinoni, P. M. Marrese, M. Montalto, J. Cabrera, C. Aerts, G. Altavilla, K. Belkacem, S. Benatti, M. Bergemann, A. Börner, G. Covone, M. Deleuil, S. Desidera, L. Gizon, M. J. Goupil, M. Günther, A. M. Heras, L. Malavolta, J. M. Mas-Hesse, D. Nardiello, H. P. Osborn, I. Pagano , et al. (8 additional authors not shown)

Abstract: The PLanetary Transits and Oscillations of stars (PLATO) mission will begin its four-year nominal mission in early 2027 by monitoring its first Long-duration Observation Phase field at South (LOPS2), for at least two years continuously. The primary aim of PLATO is a very ambitious and challenging one: the discovery of Earth-like planets in the habitable zone of nearby and bright solar analogues. T… ▽ More The PLanetary Transits and Oscillations of stars (PLATO) mission will begin its four-year nominal mission in early 2027 by monitoring its first Long-duration Observation Phase field at South (LOPS2), for at least two years continuously. The primary aim of PLATO is a very ambitious and challenging one: the discovery of Earth-like planets in the habitable zone of nearby and bright solar analogues. To this purpose, the PLATO Mission Consortium, through its Ground-based Observing Program (GOP), will perform the follow-up needed to confirm part of the candidate planets photometrically detected by PLATO and measure their masses through radial velocity curves. For the LOPS2, the GOP is committed (as part of the PLATO mission) to follow-up the candidate exoplanets discovered orbiting the 15,000 high-quality target subset of the PLATO Input Catalog (PIC) known as the Prime Sample (PS). The PS will be made public nine months before launch in the context of the first Guest Observer (GO) call for proposals to be issued by the European Space Agency (ESA). Here, we present the quantitative metrics and thresholds defined to select and prioritize the PS. Our method is perfectly general and suitable to rank any list of stars surveyed for transiting planets. We also describe the astrophysical properties of the LOPS2 PS, both in a statistical sense and for some specific targets of interest. △ Less

Submitted 3 April, 2026; originally announced April 2026.

Comments: Comments: 12 pages, 3 tables, 8 figures. Submitted to A&A

PLATO input catalogs for technical calibration and fine guidance

Authors: René Heller, Chen Jiang, Paz Bluhm, Valentina Granata, Juan Cabrera, Denis Grießbach, Carsten Paproth, Szilárd Csizmadia, Philipp Eigmüller, Paola Maria Marrese, Silvia Marinoni, Réza Samadi, Giampaolo Piotto, Marco Montalto, Martin Schäfer, Cilia Damiani, Nicholas Walton, Christoph Rauterberg, Matthias Ammler-von Eiff, Aaron C. Birch, Laurent Gizon

Abstract: A few weeks after launch, the PLATO spacecraft is expected to start its payload commissioning, which will be completed within the first three months of the mission. This phase includes the in-orbit verification, calibration, and configuration of the instrument prior to nominal science operations. During this mission-critical period, and again later during regular spacecraft rotations and re-pointi… ▽ More A few weeks after launch, the PLATO spacecraft is expected to start its payload commissioning, which will be completed within the first three months of the mission. This phase includes the in-orbit verification, calibration, and configuration of the instrument prior to nominal science operations. During this mission-critical period, and again later during regular spacecraft rotations and re-pointings, a set of reference stars is required to complete various calibration steps. This set, referred to as the calibration PLATO Input Catalog (cPIC), is part of the PIC. The cPIC comprises various stellar samples, each serving a dedicated technical calibration purpose, and it contains 71671 unique stellar targets across PLATO's entire field of view (FoV). Once the spacecraft commences science observations, the on-board Fine Guidance System (FGS) will rely on a small set of guide stars. These stars must be particularly bright and will be observed with the two fast cameras, which cover only a smaller central region of PLATO's FoV. This target list, referred to as the fine-guidance PLATO Input Catalog (fgPIC), contains 2640 unique targets, of which about 30 are used by the FGS at any given time. In this paper, we present the selection criteria for both the cPIC and the fgPIC, and asses their impact on the construction of these calibration catalogs for PLATO. △ Less

Submitted 2 April, 2026; originally announced April 2026.

Comments: submitted to Experimental Astronomy for their Special Issue on the PLATO Mission, 22 pages, 5 colored Figures, Supplementary Material: https://youtu.be/rU3fas8NFHY

Selection and characterisation of the M-dwarf targets in the PLATO Input Catalogue

Authors: L. Prisinzano, M. Montalto, G. Piotto, P. M. Marrese, S. Marinoni, V. Nascimbeni, V. Granata, J. Cabrera, K. Belkacem, M. Deleuil, L. Gizon, M. J. Goupil, I. Pagano, D. Pollacco, R. Ragazzoni, H. Rauer, S. Udry, J. Maldonado, G. Micela, F. Damiani, L. Affer, G. Altavilla, C. Argiroffi, S. Benatti, S. Cassisi , et al. (11 additional authors not shown)

Abstract: The ESA's PLAnetary Transits and Oscillations of Stars (PLATO) mission aims to detect planets orbiting around dwarfs and subgiant stars with spectral type F5 or later, including M-dwarfs. The PLATO Input Catalogue (PIC) contains all targets available for observation by the nominal science. The latest version, PIC2.1.0.1, focuses on the Southern PLATO field, named LOPS2, selected as the first long… ▽ More The ESA's PLAnetary Transits and Oscillations of Stars (PLATO) mission aims to detect planets orbiting around dwarfs and subgiant stars with spectral type F5 or later, including M-dwarfs. The PLATO Input Catalogue (PIC) contains all targets available for observation by the nominal science. The latest version, PIC2.1.0.1, focuses on the Southern PLATO field, named LOPS2, selected as the first long observation field, and includes the P4 sample, one of the four target samples outlined in the Science Requirement Document. P4 includes the M-dwarfs with magnitudes V < 16 located within LOPS2. A characterisation of the M-dwarfs in the PIC is essential for assessing their potentiality to host exoplanets, and eventually estimate the hosted planet(s) properties. The purpose of this paper is to describe how we selected the P4 M-dwarf targets, and obtained their fundamental parameters and properties. In this work, we introduce the P4 sample and detail the methodologies adopted for the measurement of their stellar parameters. Based on a statistical analysis of the P4 sample, we assess both the photometric and volume completeness, and classify the stellar populations according to their Galactic spatial-velocity components. The adopted stellar parameters are validated by comparison with independent methods from the literature used to estimate stellar radii. The P4 sample is compliant with the PLATO science requirements. Being magnitude limited, its volume completeness decreases going towards distances larger than 30 pc, where late-type targets are progressively less covered. The observed large spread in the colour-magnitude diagram is likely due to the combination of several effects such as metallicity, age, binarity and activity. The strategy we adopted for deriving stellar parameters provides results consistent with those obtained in the literature with different and independent methods. △ Less

Submitted 16 December, 2025; originally announced December 2025.

Comments: 15 pages,, 15 figures

The PLATO field selection process. II. Characterization of LOPS2, the first long-pointing field

Authors: V. Nascimbeni, G. Piotto, J. Cabrera, M. Montalto, S. Marinoni, P. M. Marrese, C. Aerts, G. Altavilla, S. Benatti, A. Börner, M. Deleuil, S. Desidera, L. Gizon, M. J. Goupil, V. Granata, A. M. Heras, D. Magrin, L. Malavolta, J. M. Mas-Hesse, H. P. Osborn, I. Pagano, C. Paproth, D. Pollacco, L. Prisinzano, R. Ragazzoni , et al. (4 additional authors not shown)

Abstract: PLAnetary Transits and Oscillations of stars (PLATO) is an ESA M-class mission to be launched by the end of 2026 to discover and characterize transiting planets around bright and nearby stars, and in particular habitable rocky planets hosted by solar-like stars. Over the mission lifetime, an average of 8% of the science data rate will be allocated to Guest Observer programs (GOs) selected by ESA t… ▽ More PLAnetary Transits and Oscillations of stars (PLATO) is an ESA M-class mission to be launched by the end of 2026 to discover and characterize transiting planets around bright and nearby stars, and in particular habitable rocky planets hosted by solar-like stars. Over the mission lifetime, an average of 8% of the science data rate will be allocated to Guest Observer programs (GOs) selected by ESA through public calls, hence it is essential for the community to know in advance where the observing fields will be located. In a previous paper, we identified two preliminary long-pointing fields (LOPN1 and LOPS1) for PLATO, respectively in the northern and southern hemisphere. Here we present LOPS2, a slightly adjusted version of the southern field that has recently been selected by the PLATO Science Working Team as the first field to be observed by PLATO for at least two continuous years, following the scientific requirements. In this paper, we describe the astrophysical content of LOPS2 in detail, including known planetary systems, bright/variable/binary stars, clusters and synergies with other current and future facilities. △ Less

Submitted 29 January, 2025; v1 submitted 13 January, 2025; originally announced January 2025.

Comments: 40 pages, 23 figures, six tables. Accepted for publication in A&A on January 11, 2025. More typos corrected. Supplementary material available on https://zenodo.org/records/14720127

Journal ref: A&A 694, A313 (2025)

The inflated, eccentric warm Jupiter TOI-4914 b orbiting a metal-poor star, and the hot Jupiters TOI-2714 b and TOI-2981 b

Authors: G. Mantovan, T. G. Wilson, L. Borsato, T. Zingales, K. Biazzo, D. Nardiello, L. Malavolta, S. Desidera, F. Marzari, A. Collier Cameron, V. Nascimbeni, F. Z. Majidi, M. Montalto, G. Piotto, K. G. Stassun, J. N. Winn, J. M. Jenkins, L. Mignon, A. Bieryla, D. W. Latham, K. Barkaoui, K. A. Collins, P. Evans, M. M. Fausnaugh, V. Granata , et al. (10 additional authors not shown)

Abstract: Recent observations of giant planets have revealed unexpected bulk densities. Hot Jupiters, in particular, appear larger than expected for their masses compared to planetary evolution models, while warm Jupiters seem denser than expected. These differences are often attributed to the influence of the stellar incident flux, but could they also result from different planet formation processes? Is th… ▽ More Recent observations of giant planets have revealed unexpected bulk densities. Hot Jupiters, in particular, appear larger than expected for their masses compared to planetary evolution models, while warm Jupiters seem denser than expected. These differences are often attributed to the influence of the stellar incident flux, but could they also result from different planet formation processes? Is there a trend linking the planetary density to the chemical composition of the host star? In this work we present the confirmation of three giant planets in orbit around solar analogue stars. TOI-2714 b ($P \simeq 2.5$ d, $R_{\rm p} \simeq 1.22 R_{\rm J}$, $M_{\rm p} = 0.72 M_{\rm J}$) and TOI-2981 b ($P \simeq 3.6$ d, $R_{\rm p} \simeq 1.2 R_{\rm J}$, $M_{\rm p} = 2 M_{\rm J}$) are hot Jupiters on nearly circular orbits, while TOI-4914 b ($P \simeq 10.6$ d, $R_{\rm p} \simeq 1.15 R_{\rm J}$, $M_{\rm p} = 0.72 M_{\rm J}$) is a warm Jupiter with a significant eccentricity ($e = 0.41 \pm 0.02$) that orbits a star more metal-poor ([Fe/H]$~= -0.13$) than most of the stars known to host giant planets. Our radial velocity (RV) follow-up with the HARPS spectrograph allows us to detect their Keplerian signals at high significance (7, 30, and 23$σ$, respectively) and to place a strong constraint on the eccentricity of TOI-4914 b (18$σ$). TOI-4914 b, with its large radius and low insolation flux ($F_\star < 2 \times 10^8~{\rm erg~s^{-1}~cm^{-2}}$), appears to be more inflated than what is supported by current theoretical models for giant planets. Moreover, it does not conform to the previously noted trend that warm giant planets orbiting metal-poor stars have low eccentricities. This study thus provides insights into the diverse orbital characteristics and formation processes of giant exoplanets, in particular the role of stellar metallicity in the evolution of planetary systems. △ Less

Submitted 11 September, 2024; originally announced September 2024.

Comments: Accepted for publication in Astronomy & Astrophysics. 21 pages, 26 figures, and 8 tables. Abstract abridged

Journal ref: A&A 691, A67 (2024)

Discovery and characterization of a dense sub-Saturn TOI-6651b

Authors: Sanjay Baliwal, Rishikesh Sharma, Abhijit Chakraborty, Akanksha Khandelwal, K. J. Nikitha, Boris S. Safonov, Ivan A. Strakhov, Marco Montalto, Jason D. Eastman, David W. Latham, Allyson Bieryla, Neelam J. S. S. V. Prasad, Kapil K. Bharadwaj, Kevikumar A. Lad, Shubhendra N. Das, Ashirbad Nayak

Abstract: We report the discovery and characterization of a transiting sub-Saturn exoplanet TOI-6651b using PARAS-2 spectroscopic observations. The host, TOI-6651 ($m_{V}\approx 10.2$), is a sub-giant, metal-rich G-type star with $[{\rm Fe/H}] = 0.225^{+0.044}_{-0.045}$, $T_{\rm eff} = 5940\pm110\ \mathrm{K}$, and $\log{g} = 4.087^{+0.035}_{-0.032}$. Joint fitting of the radial velocities from PARAS-2 spect… ▽ More We report the discovery and characterization of a transiting sub-Saturn exoplanet TOI-6651b using PARAS-2 spectroscopic observations. The host, TOI-6651 ($m_{V}\approx 10.2$), is a sub-giant, metal-rich G-type star with $[{\rm Fe/H}] = 0.225^{+0.044}_{-0.045}$, $T_{\rm eff} = 5940\pm110\ \mathrm{K}$, and $\log{g} = 4.087^{+0.035}_{-0.032}$. Joint fitting of the radial velocities from PARAS-2 spectrograph and transit photometric data from Transiting Exoplanet Survey Satellite (TESS) reveals a planetary mass of $61.0^{+7.6}_{-7.9}\ M_\oplus$ and radius of $5.09^{+0.27}_{-0.26}\ R_\oplus$, in a $5.056973^{+0.000016}_{-0.000018}$ day orbit with an eccentricity of $0.091^{+0.096}_{-0.062}$. TOI-6651b has a bulk density of $2.52^{+0.52}_{-0.44}\ \mathrm{g\ cm^{-3}}$, positioning it among the select few known dense sub-Saturns and making it notably the densest detected with TESS. TOI-6651b is consistent with the positive correlation between planet mass and the host star's metallicity. We find that a considerable portion $\approx$ 87% of the planet's mass consists of dense materials such as rock and iron in the core, while the remaining mass comprises a low-density envelope of H/He. TOI-6651b lies at the edge of the Neptunian desert, which will be crucial for understanding the factors shaping the desert boundaries. The existence of TOI-6651b challenges conventional planet formation theories and could be a result of merging events or significant atmospheric mass loss through tidal heating, highlighting the complex interplay of dynamical processes and atmospheric evolution in the formation of massive dense sub-Saturns. △ Less

Submitted 30 August, 2024; originally announced August 2024.

Comments: 15 pages, 12 figures

Journal ref: A&A, 691 (2024) A12

The PLATO Mission

Authors: Heike Rauer, Conny Aerts, Juan Cabrera, Magali Deleuil, Anders Erikson, Laurent Gizon, Mariejo Goupil, Ana Heras, Jose Lorenzo-Alvarez, Filippo Marliani, César Martin-Garcia, J. Miguel Mas-Hesse, Laurence O'Rourke, Hugh Osborn, Isabella Pagano, Giampaolo Piotto, Don Pollacco, Roberto Ragazzoni, Gavin Ramsay, Stéphane Udry, Thierry Appourchaux, Willy Benz, Alexis Brandeker, Manuel Güdel, Eduardo Janot-Pacheco , et al. (820 additional authors not shown)

Abstract: PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observati… ▽ More PLATO (PLAnetary Transits and Oscillations of stars) is ESA's M3 mission designed to detect and characterise extrasolar planets and perform asteroseismic monitoring of a large number of stars. PLATO will detect small planets (down to <2 R_(Earth)) around bright stars (<11 mag), including terrestrial planets in the habitable zone of solar-like stars. With the complement of radial velocity observations from the ground, planets will be characterised for their radius, mass, and age with high accuracy (5 %, 10 %, 10 % for an Earth-Sun combination respectively). PLATO will provide us with a large-scale catalogue of well-characterised small planets up to intermediate orbital periods, relevant for a meaningful comparison to planet formation theories and to better understand planet evolution. It will make possible comparative exoplanetology to place our Solar System planets in a broader context. In parallel, PLATO will study (host) stars using asteroseismology, allowing us to determine the stellar properties with high accuracy, substantially enhancing our knowledge of stellar structure and evolution. The payload instrument consists of 26 cameras with 12cm aperture each. For at least four years, the mission will perform high-precision photometric measurements. Here we review the science objectives, present PLATO's target samples and fields, provide an overview of expected core science performance as well as a description of the instrument and the mission profile at the beginning of the serial production of the flight cameras. PLATO is scheduled for a launch date end 2026. This overview therefore provides a summary of the mission to the community in preparation of the upcoming operational phases. △ Less

Submitted 18 November, 2024; v1 submitted 8 June, 2024; originally announced June 2024.

The GAPS programme at TNG. LVII. TOI-5076b: A warm sub-Neptune planet orbiting a thin-to-thick-disk transition star in a wide binary system

Authors: M. Montalto, N. Greco, K. Biazzo, S. Desidera, G. Andreuzzi, A. Bieryla, A. Bignamini, A. S. Bonomo, C. Briceño, L. Cabona, R. Cosentino, M. Damasso, A. Fiorenzano, W. Fong, B. Goeke, K. M. Hesse, V. B. Kostov, A. F. Lanza, D. W. Latham, N. Law, L. Mancini, A. Maggio, M. Molinaro, A. W. Mann, G. Mantovan , et al. (14 additional authors not shown)

Abstract: Aims. We report the confirmation of a new transiting exoplanet orbiting the star TOI-5076. Methods. We present our vetting procedure and follow-up observations which led to the confirmation of the exoplanet TOI-5076b. In particular, we employed high-precision {\it TESS} photometry, high-angular-resolution imaging from several telescopes, and high-precision radial velocities from HARPS-N. Results.… ▽ More Aims. We report the confirmation of a new transiting exoplanet orbiting the star TOI-5076. Methods. We present our vetting procedure and follow-up observations which led to the confirmation of the exoplanet TOI-5076b. In particular, we employed high-precision {\it TESS} photometry, high-angular-resolution imaging from several telescopes, and high-precision radial velocities from HARPS-N. Results. From the HARPS-N spectroscopy, we determined the spectroscopic parameters of the host star: T$\rm_{eff}$=(5070$\pm$143) K, log~g=(4.6$\pm$0.3), [Fe/H]=(+0.20$\pm$0.08), and [$α$/Fe]=0.05$\pm$0.06. The transiting planet is a warm sub-Neptune with a mass m$\rm_p=$(16$\pm$2) M$\rm_{\oplus}$, a radius r$\rm_p=$(3.2$\pm$0.1)~R$\rm_{\oplus}$ yielding a density $ρ_p$=(2.8$\pm$0.5) g cm$^{-3}$. It revolves around its star approximately every 23.445 days. Conclusions. The host star is a metal-rich, K2V dwarf, located at about 82 pc from the Sun with a radius of R$_{\star}$=(0.78$\pm$0.01) R$_{\odot}$ and a mass of M$_{\star}$=(0.80$\pm$0.07) M$_{\odot}$. It forms a common proper motion pair with an M-dwarf companion star located at a projected separation of 2178 au. The chemical analysis of the host-star and the Galactic-space velocities indicate that TOI-5076 belongs to the old population of thin-to-thick-disk transition stars. The density of TOI-5076b suggests the presence of a large fraction by volume of volatiles overlying a massive core. We found that a circular orbit solution is marginally favored with respect to an eccentric orbit solution for TOI-5076b. △ Less

Submitted 29 May, 2024; originally announced May 2024.

Comments: Accepted by Astronomy & Astrophysics: 15 pages, 19 figures, 4 tables

PLATO on the shoulders of TESS: analyzing mono-transit planet candidates in TESS data as a prior knowledge for PLATO observations

Authors: Christian Magliano, Giovanni Covone, Valerio Nascimbeni, Laura Inno, Jose I. Vines, Veselin Kostov, Stefano Fiscale, Valentina Granata, Marco Montalto, Isabella Pagano, Giampaolo Piotto, Vito Saggese

Abstract: The Transiting Exoplanet Survey Satellite (TESS) and the upcoming PLATO mission (PLAnetary Transits and Oscillations of stars) represent two space-based missions with complementary objectives in the field of exoplanet science. While TESS aims at detecting and characterizing exoplanets around bright and nearby stars on a relative short-period orbit, PLATO will discover a wide range of exoplanets in… ▽ More The Transiting Exoplanet Survey Satellite (TESS) and the upcoming PLATO mission (PLAnetary Transits and Oscillations of stars) represent two space-based missions with complementary objectives in the field of exoplanet science. While TESS aims at detecting and characterizing exoplanets around bright and nearby stars on a relative short-period orbit, PLATO will discover a wide range of exoplanets including rocky planets within the habitable zones of their stars. We analyze mono-transit events in TESS data around stars that will or could be monitored by the PLATO mission, offering a unique opportunity to bridge the knowledge gap between the two missions and gain deeper insights into exoplanet demographics and system architectures. We found $48$ TESS mono-transit events around stars contained in the all-sky PLATO Input Catalog; of these, at least four will be imaged on the first long-pointing PLATO field, LOPS2. We uniformly vetted this sample to rule out possible false positive detections thus removing $10$ signals from the original sample. We developed an analytic method which allows us to estimate both the orbital period and inclination of a mono-transit planet candidate using only the shape of the transit. We derived the orbital period and inclination estimates for $30$ TESS mono-transit planet candidates. Finally, we investigated whether these candidates are amenable targets for a CHEOPS observing campaign. △ Less

Submitted 18 January, 2024; originally announced January 2024.

Comments: 20 pages, 15 Figures, 4 tables. Accepted for publication on MNRAS

The GAPS programme at TNG XLIX. TOI-5398, the youngest compact multi-planet system composed of an inner sub-Neptune and an outer warm Saturn

Authors: G. Mantovan, L. Malavolta, S. Desidera, T. Zingales, L. Borsato, G. Piotto, A. Maggio, D. Locci, D. Polychroni, D. Turrini, M. Baratella, K. Biazzo, D. Nardiello, K. Stassun, V. Nascimbeni, S. Benatti, A. Anna John, C. Watkins, A. Bieryla, J. J. Lissauer, J. D. Twicken, A. F. Lanza, J. N. Winn, S. Messina, M. Montalto , et al. (46 additional authors not shown)

Abstract: Short-period giant planets are frequently found to be solitary compared to other classes of exoplanets. Small inner companions to giant planets with $P \lesssim$ 15 days are known only in five compact systems: WASP-47, Kepler-730, WASP-132, TOI-1130, and TOI-2000. Here, we report the confirmation of TOI-5398, the youngest compact multi-planet system composed of a hot sub-Neptune (TOI-5398 c,… ▽ More Short-period giant planets are frequently found to be solitary compared to other classes of exoplanets. Small inner companions to giant planets with $P \lesssim$ 15 days are known only in five compact systems: WASP-47, Kepler-730, WASP-132, TOI-1130, and TOI-2000. Here, we report the confirmation of TOI-5398, the youngest compact multi-planet system composed of a hot sub-Neptune (TOI-5398 c, $P_{\rm c}$ = 4.77271 days) orbiting interior to a short-period Saturn (TOI-5398 b, $P_{\rm b}$ = 10.590547 days) planet, both transiting around a 650 $\pm$ 150 Myr G-type star. As part of the GAPS Young Object project, we confirmed and characterised this compact system, measuring the radius and mass of both planets, thus constraining their bulk composition. Using multidimensional Gaussian processes, we simultaneously modelled stellar activity and planetary signals from TESS Sector 48 light curve and our HARPS-N radial velocity time series. We have confirmed the planetary nature of both planets, TOI-5398 b and TOI-5398 c, alongside a precise estimation of stellar parameters. Through the use of astrometric, photometric, and spectroscopic observations, our findings indicate that TOI-5398 is a young, active G dwarf star (650 $\pm$ 150 Myr), with a rotational period of $P_{\rm rot}$ = 7.34 days. The transit photometry and radial velocity measurements enabled us to measure both the radius and mass of planets b, $R_b = 10.30\pm0.40 R_{\oplus}$, $M_b = 58.7\pm5.7 M_{\oplus}$, and c, $R_c = 3.52 \pm 0.19 R_{\oplus}$, $M_c = 11.8\pm4.8 M_{\oplus}$. TESS observed TOI-5398 during sector 48 and no further observations are planned in the current Extended Mission, making our ground-based light curves crucial for ephemeris improvement. With a Transmission Spectroscopy Metric value of around 300, TOI-5398 b is the most amenable warm giant (10 < $P$ < 100 days) for JWST atmospheric characterisation. △ Less

Submitted 25 October, 2023; originally announced October 2023.

Comments: 29 pages, Paper accepted for publication in Astronomy & Astrophysics

Margherita Hack's Astrophysics at the Asiago Astrophysical Observatory

Authors: G. Umbriaco, A. Bianchini, A. Pizzella, A. Siviero, G. Coran, P. Ochner, M. Montalto, M. Bazzicalupo, P. Colasanto

Abstract: Margherita Hack observed with the Galileo telescope at the Asiago Astrophysical Observatory from September 1951 to March 1954. Using the spectroscopic facilities of the observatory, Margherita contributed to the stellar study of novae, symbiotic stars, and peculiar stars. In the 80th anniversary of the Asiago Astrophysical Observatory and the 100th year of Margherita, we found her observations in… ▽ More Margherita Hack observed with the Galileo telescope at the Asiago Astrophysical Observatory from September 1951 to March 1954. Using the spectroscopic facilities of the observatory, Margherita contributed to the stellar study of novae, symbiotic stars, and peculiar stars. In the 80th anniversary of the Asiago Astrophysical Observatory and the 100th year of Margherita, we found her observations in the Asiago Photographic Plate Archive and we remade some Margherita's observations with the current capabilities of Asiago telescopes. We present here a summary of the early studies carried out by Margherita with the Galileo telescope. We underline the importance of maintaining a well-organised plate archive to allow historical and scientifi c studies. △ Less

Submitted 23 August, 2023; v1 submitted 22 August, 2023; originally announced August 2023.

Comments: Conference paper "HACK100: Past, Present and Future of Astrophysical Spectroscopy", International Conference, Trieste, 6-10 June 2022

A study of two periodogram algorithms for improving the detection of small transiting planets

Authors: Yash Gondhalekar, Eric D. Feigelson, Gabriel A. Caceres, Marco Montalto, Snehanshu Saha

Abstract: The sensitivities of two periodograms are compared for weak signal planet detection in transit surveys: the widely used Box-Least Squares (BLS) algorithm following light curve detrending and the Transit Comb Filter (TCF) algorithm following autoregressive ARIMA modeling. Small depth transits are injected into light curves with different simulated noise characteristics. Two measures of spectral pea… ▽ More The sensitivities of two periodograms are compared for weak signal planet detection in transit surveys: the widely used Box-Least Squares (BLS) algorithm following light curve detrending and the Transit Comb Filter (TCF) algorithm following autoregressive ARIMA modeling. Small depth transits are injected into light curves with different simulated noise characteristics. Two measures of spectral peak significance are examined: the periodogram signal-to-noise ratio (SNR) and a False Alarm Probability (FAP) based on the generalized extreme value distribution. The relative performance of the BLS and TCF algorithms for small planet detection is examined for a range of light curve characteristics, including orbital period, transit duration, depth, number of transits, and type of noise. We find that the TCF periodogram applied to ARIMA fit residuals with the SNR detection metric is preferred when short-memory autocorrelation is present in the detrended light curve and even when the light curve noise had white Gaussian noise. BLS is more sensitive to small planets only under limited circumstances with the FAP metric. BLS periodogram characteristics are inferior when autocorrelated noise is present due to heteroscedastic noise and false period detection. Application of these methods to TESS light curves with known small exoplanets confirms our simulation results. The study ends with a decision tree that advises transit survey scientists on procedures to detect small planets most efficiently. The use of ARIMA detrending and TCF periodograms can significantly improve the sensitivity of any transit survey with regularly spaced cadence. △ Less

Submitted 12 December, 2023; v1 submitted 8 August, 2023; originally announced August 2023.

Comments: 30 pages, 13 figures, accepted for publication in ApJL

Hyades Member K2-136c: The Smallest Planet in an Open Cluster with a Precisely Measured Mass

Authors: Andrew W. Mayo, Courtney D. Dressing, Andrew Vanderburg, Charles D. Fortenbach, Florian Lienhard, Luca Malavolta, Annelies Mortier, Alejandro Núñez, Tyler Richey-Yowell, Emma V. Turtelboom, Aldo S. Bonomo, David W. Latham, Mercedes López-Morales, Evgenya Shkolnik, Alessandro Sozzetti, Marcel A. Agüeros, Luca Borsato, David Charbonneau, Rosario Cosentino, Stephanie T. Douglas, Xavier Dumusque, Adriano Ghedina, Rose Gibson, Valentina Granata, Avet Harutyunyan , et al. (17 additional authors not shown)

Abstract: K2-136 is a late-K dwarf ($0.742\pm0.039$ M$_\odot$) in the Hyades open cluster with three known, transiting planets and an age of $650\pm70$ Myr. Analyzing K2 photometry, we found that planets K2-136b, c, and d have periods of $8.0$, $17.3$, and $25.6$ days and radii of $1.014\pm0.050$ R$_\oplus$, $3.00\pm0.13$ R$_\oplus$, and $1.565\pm0.077$ R$_\oplus$, respectively. We collected 93 radial veloc… ▽ More K2-136 is a late-K dwarf ($0.742\pm0.039$ M$_\odot$) in the Hyades open cluster with three known, transiting planets and an age of $650\pm70$ Myr. Analyzing K2 photometry, we found that planets K2-136b, c, and d have periods of $8.0$, $17.3$, and $25.6$ days and radii of $1.014\pm0.050$ R$_\oplus$, $3.00\pm0.13$ R$_\oplus$, and $1.565\pm0.077$ R$_\oplus$, respectively. We collected 93 radial velocity measurements (RVs) with the HARPS-N spectrograph (TNG) and 22 RVs with the ESPRESSO spectrograph (VLT). Analyzing HARPS-N and ESPRESSO data jointly, we found K2-136c induced a semi-amplitude of $5.49\pm0.53$ m s$^{-1}$, corresponding to a mass of $18.1\pm1.9$ M$_\oplus$. We also placed $95$% upper mass limits on K2-136b and d of $4.3$ and $3.0$ M$_\oplus$, respectively. Further, we analyzed HST and XMM-Newton observations to establish the planetary high-energy environment and investigate possible atmospheric loss. K2-136c is now the smallest planet to have a measured mass in an open cluster and one of the youngest planets ever with a mass measurement. K2-136c has $\sim$75% the radius of Neptune but is similar in mass, yielding a density of $3.69^{+0.67}_{-0.56}$ g cm$^{-3}$ ($\sim$2-3 times denser than Neptune). Mass estimates for K2-136b (and possibly d) may be feasible with more RV observations, and insights into all three planets' atmospheres through transmission spectroscopy would be challenging but potentially fruitful. This research and future mass measurements of young planets are critical for investigating the compositions and characteristics of small exoplanets at very early stages of their lives and providing insights into how exoplanets evolve with time. △ Less

Submitted 5 April, 2023; originally announced April 2023.

Comments: Accepted in AJ, 25 pages, 10 figures, 5 tables

DIAmante TESS AutoRegressive Planet Search (DTARPS): III. Understanding the DTARPS Candidate Transiting Planet Catalogs

Authors: Elizabeth J. Melton, Eric D. Feigelson, Marco Montalto, Gabriel A. Caceres, Andrew W. Rosenswie, Cullen S. Abelson

Abstract: The DIAmante TESS AutoRegressive Planet Search (DTARPS) project, using novel statistical methods, has identified several hundred candidates for transiting planetary systems obtained from 0.9 million Full Frame Image light curves obtained in the TESS Year 1 southern hemisphere survey (Melton et al. 2024a and 2024b). Several lines of evidence, including limited reconnaissance spectroscopy, indicate… ▽ More The DIAmante TESS AutoRegressive Planet Search (DTARPS) project, using novel statistical methods, has identified several hundred candidates for transiting planetary systems obtained from 0.9 million Full Frame Image light curves obtained in the TESS Year 1 southern hemisphere survey (Melton et al. 2024a and 2024b). Several lines of evidence, including limited reconnaissance spectroscopy, indicate that at least half are true planets rather than False Positives. Here various population properties of these objects are examined. Half of the DTARPS candidates are hot Neptunes, populating the 'Neptune desert' found in Kepler planet samples. The DTARPS samples also identify dozens of Ultra Short Period planets with orbital periods down to 5 hours, high priority systems for atmospheric transimssion spectroscopy, and planets orbiting low-mass M stars. DTARPS methodology is sufficiently well-characterized at each step that preliminary planet occurrence rates can be estimated. Except for the increase in hot Neptunes, DTARPS planet occurrence rates are consistent with Kepler rates. Overall, DTARPS provides one of the largest and most reliable catalog of TESS exoplanet candidates that can be tapped to improve our understanding of various exoplanetary populations and astrophysical processes. △ Less

Submitted 27 September, 2024; v1 submitted 13 February, 2023; originally announced February 2023.

Comments: 37 pages, 19 figures, accepted for publication in The Astronomical Journal, September 2024

DIAmante TESS AutoRegressive Planet Search (DTARPS): II. Hundreds of New TESS Candidate Exoplanets

Authors: Elizabeth J. Melton, Eric D. Feigelson, Marco Montalto, Gabriel A. Caceres, Andrew W. Rosenswie, Cullen S. Abelson

Abstract: The DIAmante TESS AutoRegressive Planet Search (DTARPS) project seeks to identify photometric transiting planets from 976,814 southern hemisphere stars observed in Year 1 of the TESS mission. This paper follows the methodology developed by Melton et al. (Paper I) using light curves extracted and pre-processed by the DIAmante project (Montalto et al. 2020). Paper I emerged with a list of 7,377 ligh… ▽ More The DIAmante TESS AutoRegressive Planet Search (DTARPS) project seeks to identify photometric transiting planets from 976,814 southern hemisphere stars observed in Year 1 of the TESS mission. This paper follows the methodology developed by Melton et al. (Paper I) using light curves extracted and pre-processed by the DIAmante project (Montalto et al. 2020). Paper I emerged with a list of 7,377 light curves with statistical properties characteristic of transiting planets but dominated by False Alarms and False Positives. Here a multistage vetting procedure is applied including: centroid motion and crowding metrics, False Alarm and False Positive reduction, photometric binary elimination, and ephemeris match removal. The vetting produces a catalog of 462 DTARPS Candidates across the southern ecliptic hemisphere and 310 objects in a spatially incomplete Galactic Plane list. Fifty-eight percent were not previously identified as transiting systems. Candidates are flagged for possible blending from nearby stars based on Zwicky Transient Facility data and for possible radial velocity variations based on Gaia satellite data. Orbital periods and planetary radii are refined using astrophysical modeling; the resulting parameters closely match published values for Confirmed Planets. Their properties are discussed in Paper III. △ Less

Submitted 10 April, 2024; v1 submitted 13 February, 2023; originally announced February 2023.

Comments: 34 pages, 11 figures. Published in The Astronomical Journal. Machine Readable Tables for the DTARPS-S Candidate Catalog is available at https://content.cld.iop.org/journals/1538-3881/167/5/203/revision1/ajad29f1t1_mrt.txt with Figure Set at .../ajad29f1figset5.tar.gz. The DTARPS-S Galactic Plane List is available at https://.../ajad29f1t4_mrt.txt with Figure Set .../ajad29f1figset10.tar.gz

Journal ref: Astronomical Journal, 167, 203, 2024

DIAmante TESS AutoRegressive Planet Search (DTARPS): I. Analysis of 0.9 Million Light Curves

Authors: Elizabeth J. Melton, Eric D. Feigelson, Marco Montalto, Gabriel A. Caceres, Andrew W. Rosenswie, Cullen S. Abelson

Abstract: Nearly one million light curves from the TESS Year 1 southern hemisphere extracted from Full Frame Images with the DIAmante pipeline are processed through the AutoRegressive Planet Search statistical procedure. ARIMA models remove trends and lingering autocorrelated noise, the Transit Comb Filter identifies the strongest periodic signal in the light curve, and a Random Forest machine learning clas… ▽ More Nearly one million light curves from the TESS Year 1 southern hemisphere extracted from Full Frame Images with the DIAmante pipeline are processed through the AutoRegressive Planet Search statistical procedure. ARIMA models remove trends and lingering autocorrelated noise, the Transit Comb Filter identifies the strongest periodic signal in the light curve, and a Random Forest machine learning classifier is trained and applied to identify the best potential candidates. Classifier training sets include injections of both planetary transit signals and contaminating eclipsing binaries. The optimized classifier has a True Positive Rate of 92.8% and a False Positive Rate of 0.37% from the labeled training set. The result of this DIAmante TESS autoregressive planet search (DTARPS) analysis is a list of 7,377 potential exoplanet candidates. The classifier has a False Positive Rate of 0.3%, a 64% recall rate for previously confirmed exoplanets, and a 78% negative recall rate for known False Positives. The completeness map of the injected planetary signals shows high recall rates for planets with 8 - 30 R(Earth) radii and periods 0.6-13 days and poor completeness for planets with radii < 2 R(Earth) or periods < 1 day. The list has many False Alarms and False Positives that need to be culled with multifaceted vetting operations (Paper II). △ Less

Submitted 11 April, 2024; v1 submitted 13 February, 2023; originally announced February 2023.

Comments: 34 pages, 24 figures. Published in The Astronomical Journal, 2024 May. A Machine Readable Table for Table 3 is available at https://content.cld.iop.org/journals/1538-3881/167/5/202/revision1/ajad29f0t3_mrt.txt

Journal ref: The Astronomical Journal, 167:203, 2024

New members of the Lupus I cloud based on Gaia astrometry Physical and accretion properties from X-Shooter spectra

Authors: F. Z. Majidi, J. M. Alcala', A. Frasca, S. Desidera, C. F. Manara, G. Beccari, V. D'Orazi, A. Bayo, K. Biazzo, R. Claudi, E. Covino, G. Mantovan, M. Montalto, D. Nardiello, G. Piotto, E. Rigliaco

Abstract: We characterize twelve young stellar objects (YSOs) located in the Lupus I region, spatially overlapping with the Upper Centaurus Lupus (UCL) sub-stellar association. The aim of this study is to understand whether the Lupus I cloud has more members than what has been claimed so far in the literature and gain a deeper insight into the global properties of the region. We selected our targets using G… ▽ More We characterize twelve young stellar objects (YSOs) located in the Lupus I region, spatially overlapping with the Upper Centaurus Lupus (UCL) sub-stellar association. The aim of this study is to understand whether the Lupus I cloud has more members than what has been claimed so far in the literature and gain a deeper insight into the global properties of the region. We selected our targets using Gaia DR2 catalog, based on their consistent kinematic properties with the Lupus I bona fide members. In our sample of twelve YSOs observed by X-Shooter, we identified ten Lupus I members. We could not determine the membership status of two of our targets, namely Gaia DR2 6014269268967059840 and 2MASS J15361110-3444473 due to technical issues. We found out that four of our targets are accretors, among them 2MASS J15551027-3455045, with a mass of ~0.03 M_Sun, is one of the least massive accretors in the Lupus complex to date. Several of our targets (including accretors) are formed in-situ and off-cloud with respect to the main filaments of Lupus I, hence, our study may hint that there are diffused populations of M-dwarfs around Lupus I main filaments. In this context, we would like to emphasize that our kinematic analysis with Gaia catalogs played a key role in identifying the new members of the Lupus I cloud. △ Less

Submitted 11 January, 2023; originally announced January 2023.

Comments: 20 pages, 15 Tables, 13 Figures, accepted for publication in A&A

Journal ref: A&A 671, A46 (2023)

A search for planetary transits on a set of 1.4 million multi-sector DIAmante lightcurves

Authors: M. Montalto

Abstract: I report the results of a new search for transiting planets on a set of 1.4 million lightcurves extracted from TESS Full Frame Images (FFIs) using the DIAmante pipeline. The data come from the first two years of observations of TESS (Sectors 1-26) and the study is focused on a sample of FGKM dwarf and subgiant stars optimized for the search of transiting planets. The search was performed on the de… ▽ More I report the results of a new search for transiting planets on a set of 1.4 million lightcurves extracted from TESS Full Frame Images (FFIs) using the DIAmante pipeline. The data come from the first two years of observations of TESS (Sectors 1-26) and the study is focused on a sample of FGKM dwarf and subgiant stars optimized for the search of transiting planets. The search was performed on the detrended and stitched multi-sector lightcurves applying the Box-fitting Least Squares algorithm and a Random Forest classifier. I present a catalogue of 1160 transiting planet candidates, among which 842 are novel discoveries. The median radius of the transiting bodies in the catalog is 6.8 R$_{\oplus}$. The radii range from 0.8 R$_{\oplus}$ to 27.3R$_{\oplus}$ while the orbital periods range from 0.19 days to 197.2 days with a median of 3.6 days. Each candidate is accompained by a validation report and the corresponding DIAmante lightcurve. The material is available at CDS, on the ExoFOP website and on the DIAmante portal at MAST. △ Less

Submitted 26 October, 2022; originally announced October 2022.

Comments: Accepted by MNRAS

The GAPS Programme at TNG. XLI. The climate of KELT-9b revealed with a new approach to high spectral resolution phase curves

Authors: L. Pino, M. Brogi, J. M. Désert, V. Nascimbeni, A. S. Bonomo, E. Rauscher, M. Basilicata, K. Biazzo, A. Bignamini, F. Borsa, R. Claudi, E. Covino, M. P. Di Mauro, G. Guilluy, A. Maggio, L. Malavolta, G. Micela, E. Molinari, M. Molinaro, M. Montalto, D. Nardiello, M. Pedani, G. Piotto, E. Poretti, M. Rainer , et al. (3 additional authors not shown)

Abstract: [Abridged] We present a novel method to study the thermal emission of exoplanets as a function of orbital phase at very high spectral resolution, and apply it to investigate the climate of the ultra-hot Jupiter KELT-9b. We combine 3 nights of HARPS-N and 2 nights of CARMENES optical spectra, covering orbital phases between quadratures (0.25 < phi < 0.75), when the planet shows its day-side hemisph… ▽ More [Abridged] We present a novel method to study the thermal emission of exoplanets as a function of orbital phase at very high spectral resolution, and apply it to investigate the climate of the ultra-hot Jupiter KELT-9b. We combine 3 nights of HARPS-N and 2 nights of CARMENES optical spectra, covering orbital phases between quadratures (0.25 < phi < 0.75), when the planet shows its day-side hemisphere with different geometries. We co-add the signal of thousands of FeI lines through cross-correlation, which we map to a likelihood function. We investigate the phase-dependence of: (i) the line depths of FeI, and (ii) their Doppler shifts, by introducing a new method that exploits the very high spectral resolution of our observations. We confirm a previous detection of FeI emission and demonstrate a combined precision of 0.5 km s-1 on the orbital properties of KELT-9b. By studying the phase-resolved Doppler shift of FeI lines, we detect an anomaly in the planet's orbital radial velocity well-fitted with a slightly eccentric orbit (e = 0.016$\pm$0.003, w = 150$^{+13\circ}_{-11},~5σ$ preference). However, we argue that such anomaly can be explained by a day-night wind of a few km s-1 blowing neutral iron gas. Additionally, we find that the FeI emission line depths are symmetric around the substellar point within 10 deg ($2σ$). We show that these results are qualitatively compatible with predictions from general circulation models for ultra-hot Jupiter planets. Very high-resolution spectroscopy phase curves have the sensitivity to reveal a phase dependence in both the line depths and their Doppler shifts throughout the orbit. They are highly complementary to space-based phase curves obtained with HST and JWST, and open a new window into the still poorly understood climate and atmospheric structure of the hottest planets known. △ Less

Submitted 23 September, 2022; originally announced September 2022.

Comments: Recommended for publication on A&A after referee report, awaiting acceptance. 25 pages, 19 figures, 3 tables

Journal ref: A&A 668, A176 (2022)

Validation of TESS exoplanet candidates orbiting solar analogues in the all-sky PLATO input catalogue

Authors: Giacomo Mantovan, Marco Montalto, Giampaolo Piotto, Thomas G. Wilson, Andrew Collier Cameron, Fatemeh Zahra Majidi, Luca Borsato, Valentina Granata, Valerio Nascimbeni

Abstract: The Transiting Exoplanet Survey Satellite (TESS) is focusing on relatively bright stars and has found thousands of planet candidates. However, mainly because of the low spatial resolution of its cameras ($\approx$ 21 arcsec/pixel), TESS is expected to detect several false positives (FPs); hence, vetting needs to be done. Here, we present a follow-up program of TESS candidates orbiting solar-analog… ▽ More The Transiting Exoplanet Survey Satellite (TESS) is focusing on relatively bright stars and has found thousands of planet candidates. However, mainly because of the low spatial resolution of its cameras ($\approx$ 21 arcsec/pixel), TESS is expected to detect several false positives (FPs); hence, vetting needs to be done. Here, we present a follow-up program of TESS candidates orbiting solar-analogue stars that are in the all-sky PLATO input catalogue. Using Gaia photometry and astrometry we built an absolute colour-magnitude diagram and isolated solar-analogue candidates' hosts. We performed a probabilistic validation of each candidate using the VESPA software and produced a prioritized list of objects that have the highest probability of being genuine transiting planets. Following this procedure, we eliminated the majority of FPs and statistically vetted 23 candidates. For this remaining set, we performed a stellar neighbourhood analysis using Gaia Early Data Release 3 and centroid motion tests, greatly enhancing the on-target probability of 12 of them. We then used publicly available high-resolution imaging data to confirm their transit source and found five new, fully validated planets. For the remaining candidates, we propose on-off photometry to further refine the list of genuine candidates and prepare for the subsequent radial velocity follow-up. △ Less

Submitted 25 August, 2022; originally announced August 2022.

Comments: 16 pages, 11 figures. Accepted for publication in MNRAS on 2022 August 23

The PLATO field selection process I. Identification and content of the long-pointing fields

Authors: V. Nascimbeni, G. Piotto, A. Börner, M. Montalto, P. M. Marrese, J. Cabrera, S. Marinoni, C. Aerts, G. Altavilla, S. Benatti, R. Claudi, M. Deleuil, S. Desidera, M. Fabrizio, L. Gizon, M. J. Goupil, V. Granata, A. M. Heras, D. Magrin, L. Malavolta, J. M. Mas-Hesse, S. Ortolani, I. Pagano, D. Pollacco, L. Prisinzano , et al. (4 additional authors not shown)

Abstract: PLATO (PLAnetary Transits and Oscillations of stars) is an ESA M-class satellite planned for launch by end 2026 and dedicated to the wide-field search of transiting planets around bright and nearby stars, with a strong focus on discovering habitable rocky planets hosted by solar-like stars. The choice of the fields to be pointed at is a crucial task since it has a direct impact on the scientific r… ▽ More PLATO (PLAnetary Transits and Oscillations of stars) is an ESA M-class satellite planned for launch by end 2026 and dedicated to the wide-field search of transiting planets around bright and nearby stars, with a strong focus on discovering habitable rocky planets hosted by solar-like stars. The choice of the fields to be pointed at is a crucial task since it has a direct impact on the scientific return of the mission. In this paper we describe and discuss the formal requirements and the key scientific prioritization criteria that have to be taken into account in the Long-duration Observation Phase (LOP) field selection, and apply a quantitative metric to guide us in this complex optimization process. We identify two provisional LOP fields, one for each hemisphere (LOPS1, LOPN1), and discuss their properties and stellar content. While additional fine-tuning shall be applied to LOP selection before the definitive choice (to be made two years before launch), we expect their position will not move by more than a few degrees with respect to what is proposed in this paper. △ Less

Submitted 23 December, 2021; v1 submitted 26 October, 2021; originally announced October 2021.

Comments: 17 pages, 10 figures, 3 tables, A&A in press (accepted: October 26, 2021). Some typos corrected. Author list corrected

Journal ref: A&A 658, A31 (2022)

TIC~257060897b: an inflated, low-density, hot-Jupiter transiting a rapidly evolving subgiant star

Authors: M. Montalto, L. Malavolta, J. Gregorio, G. Mantovan, S. Desidera, G. Piotto, V. Nascimbeni, V. Granata, E. E. Manthopoulou, R. Claudi

Abstract: We report the discovery of a new transiting exoplanet orbiting the star TIC~257060897 and detected using {\it TESS} full frame images. We acquired HARPS-N time-series spectroscopic data, and ground-based photometric follow-up observations from which we confirm the planetary nature of the transiting body. For the host star we determined: T$\rm_{eff}$=(6128$\pm$57) K, log~g=(4.2$\pm$0.1) and [Fe/H]=… ▽ More We report the discovery of a new transiting exoplanet orbiting the star TIC~257060897 and detected using {\it TESS} full frame images. We acquired HARPS-N time-series spectroscopic data, and ground-based photometric follow-up observations from which we confirm the planetary nature of the transiting body. For the host star we determined: T$\rm_{eff}$=(6128$\pm$57) K, log~g=(4.2$\pm$0.1) and [Fe/H]=(+0.20$\pm$0.04). The host is an intermediate age ($\sim$3.5~Gyr), metal-rich, subgiant star with M$_{\star}$=(1.32$\pm$0.04) M$_{\odot}$ and R$_{\star}$=(1.82$\pm$0.05) R$_{\odot}$. The transiting body is a giant planet with a mass m$\rm_p=$(0.67$\pm$0.03) M$\rm_{j}$, a radius r$\rm_p=$(1.49$\pm$0.04) R$\rm_{j}$ yielding a density $ρ_p$=(0.25$\pm$0.02) g cm$^{-3}$ and revolving around its star every $\sim$3.66 days. TIC~257060897b is an extreme system having one of the smallest densities known so far. We argued that the inflation of the planet's radius may be related to the fast increase of luminosity of its host star as it evolves outside the main sequence and that systems like TIC~257060897b could be precursors of inflated radius short period planets found around low luminosity red giant branch stars, as recently debated in the literature. △ Less

Submitted 1 October, 2021; originally announced October 2021.

Comments: Accepted for publication in MNRAS

The all-sky PLATO input catalogue

Authors: M. Montalto, G. Piotto, P. M. Marrese, V. Nascimbeni, L. Prisinzano, V. Granata, S. Marinoni, S. Desidera, S. Ortolani, C. Aerts, E. Alei, G. Altavilla, S. Benatti, A. Börner, J. Cabrera, R. Claudi, M. Deleuil, M. Fabrizio, L. Gizon, M. J. Goupil, A. M. Heras, D. Magrin, L. Malavolta, J. M. Mas-Hesse, I. Pagano , et al. (7 additional authors not shown)

Abstract: Context. The ESA PLAnetary Transits and Oscillations of stars (PLATO) mission will search for terrestrial planets in the habitable zone of solar-type stars. Because of telemetry limitations, PLATO targets need to be pre-selected. Aims. In this paper, we present an all sky catalogue that will be fundamental to selecting the best PLATO fields and the most promising target stars, deriving their basic… ▽ More Context. The ESA PLAnetary Transits and Oscillations of stars (PLATO) mission will search for terrestrial planets in the habitable zone of solar-type stars. Because of telemetry limitations, PLATO targets need to be pre-selected. Aims. In this paper, we present an all sky catalogue that will be fundamental to selecting the best PLATO fields and the most promising target stars, deriving their basic parameters, analysing the instrumental performances, and then planing and optimising follow-up observations. This catalogue also represents a valuable resource for the general definition of stellar samples optimised for the search of transiting planets. Methods. We used Gaia Data Release 2 (DR2) astrometry and photometry and 3D maps of the local interstellar medium to isolate FGK (V$\leq$13) and M (V$\leq$16) dwarfs and subgiant stars. Results. We present the first public release of the all-sky PLATO Input Catalogue (asPIC1.1) containing a total of 2 675 539 stars including 2 378 177 FGK dwarfs and subgiants and 297 362 M dwarfs. The median distance in our sample is 428 pc for FGK stars and 146 pc for M dwarfs, respectively. We derived the reddening of our targets and developed an algorithm to estimate stellar fundamental parameters (Teff, radius, mass) from astrometric and photometric measurements. Conclusions. We show that the overall (internal+external) uncertainties on the stellar parameter determined in the present study are $\sim$230 K (4%) for the effective temperatures, $\sim$0.1 R$_{\odot}$ (9%) for the stellar radii, and $\sim$0.1 M$_{\odot}$ (11%) for the stellar mass. We release a special target list containing all known planet hosts cross-matched with our catalogue. △ Less

Submitted 31 August, 2021; originally announced August 2021.

Comments: Accepted for publication in Astronomy & Astrophysics

Journal ref: A&A 653, A98 (2021)

The GAPS Programme at TNG XXVIII -- A pair of hot-Neptunes orbiting the young star TOI-942

Authors: Ilaria Carleo, Silvano Desidera, Domenico Nardiello, Luca Malavolta, Antonino F. Lanza, John Livingston, Daniele Locci, Francesco Marzari, Sergio Messina, Diego Turrini, Martina Baratella, Francesco Borsa, Valentina D'Orazi, Valerio Nascimbeni, Matteo Pinamonti, Monica Rainer, Eleonora Alei, Andrea Bignamini, Raffaele Gratton, Giuseppina Micela, Marco Montalto, Alessandro Sozzetti, Vito Squicciarini, Laura Affer, Serena Benatti , et al. (26 additional authors not shown)

Abstract: Both young stars and multi-planet systems are primary objects that allow us to study, understand and constrain planetary formation and evolution theories. We validate the physical nature of two Neptune-type planets transiting TOI-942 (TYC 5909-319-1), a previously unacknowledged young star (50+30-20 Myr) observed by the TESS space mission in Sector 5. Thanks to a comprehensive stellar characteriza… ▽ More Both young stars and multi-planet systems are primary objects that allow us to study, understand and constrain planetary formation and evolution theories. We validate the physical nature of two Neptune-type planets transiting TOI-942 (TYC 5909-319-1), a previously unacknowledged young star (50+30-20 Myr) observed by the TESS space mission in Sector 5. Thanks to a comprehensive stellar characterization, TESS light curve modelling and precise radial-velocity measurements, we validated the planetary nature of the TESS candidate and detect an additional transiting planet in the system on a larger orbit. From photometric and spectroscopic observations we performed an exhaustive stellar characterization and derived the main stellar parameters. TOI-942 is a relatively active K2.5V star (logR'hk = -4.17+-0.01) with rotation period Prot = 3.39+-0.01 days, a projected rotation velocity vsini=13.8+-0.5 km/s and a radius of ~0.9 Rsun. We found that the inner planet, TOI-942b, has an orbital period Pb=4.3263+-0.0011 days, a radius Rb=4.242-0.313+0.376 Rearth and a mass upper limit of 16 Mearth at 1-sigma confidence level. The outer planet, TOI-942c, has an orbital period Pc=10.1605-0.0053+0.0056 days, a radius Rc=4.793-0.351+0.410 Rearth and a mass upper limit of 37 Mearth at 1-sigma confidence level. △ Less

Submitted 27 November, 2020; originally announced November 2020.

Journal ref: A&A 645, A71 (2021)

A search for transiting planets around FGKM dwarfs and sub-giants in the TESS Full Frame Images of the Southern ecliptic hemisphere

Authors: M. Montalto, L. Borsato, V. Granata, G. Lacedelli, L. Malavolta, E. E. Manthopoulou, D. Nardiello, V. Nascimbeni, G. Piotto

Abstract: In this work, we present the analysis of 976 814 FGKM dwarf and sub-giant stars in the TESS Full Frame Images (FFIs) of the Southern ecliptic hemisphere. We present a new pipeline, DIAmante, developed to extract optimized, multi-sector photometry from TESS FFIs and a classifier, based on the Random Forest technique, trained to discriminate plausible transiting planetary candidates from common fals… ▽ More In this work, we present the analysis of 976 814 FGKM dwarf and sub-giant stars in the TESS Full Frame Images (FFIs) of the Southern ecliptic hemisphere. We present a new pipeline, DIAmante, developed to extract optimized, multi-sector photometry from TESS FFIs and a classifier, based on the Random Forest technique, trained to discriminate plausible transiting planetary candidates from common false positives. A new statistical model was developed to provide the probability of correct identification of the source of variability. We restricted the planet search to the stars located in the least crowded regions of the sky and identified 396 transiting planetary candidates among which 252 are new detections. The candidates' radius distribution ranges between 1 R$\rm_{\oplus}$ and 2.6 R$\rm_J$ with median value of 1 R$\rm_J$ and the period distribution ranges between 0.25 days and 105 days with median value of 3.8 days. The sample contains four long period candidates (P>50 days) one of which is new and 64 candidates with periods between 10 and 50 days (42 new ones). In the small planet radius domain (R<4 R$\rm_{\oplus}$) we found 39 candidates among which 15 are new detections. Additionally, we present 15 single transit events (14 new ones), a new candidate multi-planetary system and a novel candidate around a known TOI. By using {\it Gaia} dynamical constraints we found that 70 objects show evidence of binarity. We release a catalog of the objects we analyzed and the corresponding lightcurves and diagnostic figures through the MAST and ExoFOP portals. △ Less

Submitted 22 August, 2020; originally announced August 2020.

Comments: Accepted by MNRAS. Data available at https://archive.stsci.edu/hlsp/diamante

A Plague of Magnetic Spots Among the Hot Stars of Globular Clusters

Authors: Yazan Al Momany, Simone Zaggia, Marco Montalto, David Jones, Henri M. J. Boffin, Santino Cassisi, Christian Moni Bidin, Marco Gullieuszik, Ivo Saviane, Lorenzo Monaco, Elena Mason, Leo Girardi, Valentina D'Orazi, Giampaolo Piotto, Antonino P. Milone, Hitesh Lala, Peter B. Stetson, Yuri Beletsky

Abstract: Six decades and counting, the formation of hot ~20,000-30,000 K Extreme Horizontal Branch (EHB) stars in Galactic Globular Clusters remains one of the most elusive quests in stellar evolutionary theory. Here we report on two discoveries shattering their currently alleged stable luminosity. The first EHB variability is periodic and cannot be ascribed to binary evolution nor pulsation. Instead, we h… ▽ More Six decades and counting, the formation of hot ~20,000-30,000 K Extreme Horizontal Branch (EHB) stars in Galactic Globular Clusters remains one of the most elusive quests in stellar evolutionary theory. Here we report on two discoveries shattering their currently alleged stable luminosity. The first EHB variability is periodic and cannot be ascribed to binary evolution nor pulsation. Instead, we here attribute it to the presence of magnetic spots: superficial chemical inhomogeneities whose projected rotation induces the variability. The second EHB variability is aperiodic and manifests itself on time-scales of years. In two cases, the six-year light curves display superflare events a mammoth several million times more energetic than solar analogs. We advocate a scenario where the two spectacular EHB variability phenomena are different manifestations of diffuse, dynamo-generated, weak magnetic fields. Ubiquitous magnetic fields, therefore, force an admittance into the intricate matrix governing the formation of all EHBs, and traverse to their Galactic field counterparts. The bigger picture is one where our conclusions bridge similar variability/magnetism phenomena in all radiative-enveloped stars: young main-sequence stars, old EHBs and defunct white dwarfs. △ Less

Submitted 5 June, 2020; v1 submitted 3 June, 2020; originally announced June 2020.

Comments: Author's version of the main article (23 pages) and Supplementary Information (22 pages) combined into a single pdf (45 pages). Readers invited to read the Nature Astronomy Published version available at this url: https://www.nature.com/articles/s41550-020-1113-4

A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- II. Search for exoplanets in open clusters of the southern ecliptic hemisphere and their frequency

Authors: D. Nardiello, G. Piotto, M. Deleuil, L. Malavolta, M. Montalto, L. R. Bedin, L. Borsato, V. Granata, M. Libralato, E. E. Manthopoulou

Abstract: The scope of the project "A PSF-based Approach to TESS High Quality data Of Stellar clusters" (PATHOS) is the extraction and analysis of high-precision light curves of stars in stellar clusters and young associations for the identification of candidate exoplanets and variable stars. The cutting-edge tools used in this project allow us to measure the real flux of stars in dense fields, minimising t… ▽ More The scope of the project "A PSF-based Approach to TESS High Quality data Of Stellar clusters" (PATHOS) is the extraction and analysis of high-precision light curves of stars in stellar clusters and young associations for the identification of candidate exoplanets and variable stars. The cutting-edge tools used in this project allow us to measure the real flux of stars in dense fields, minimising the effects due to contamination by neighbour sources. We extracted about 200 000 light curves of stars in 645 open clusters located in the southern ecliptic hemisphere and observed by TESS during the first year of its mission. We searched for transiting signals and we found 33 objects of interest, 11 of them are strong candidate exoplanets. Because of the limited S/N, we did not find any Earth or super-Earth. We identified two Neptune-size planets orbiting stars with $R_{\star}<1.5\,R_{\odot}$, implying a frequency $f_{\star}=1.34 \pm 0.95\,\%$, consistent with the frequency around field stars. The 7 Jupiter candidates around stars with $R_{\star}<\,1.5R_{\odot}$ imply a frequency $f_{\star}=0.19\pm 0.07\,\%$, smaller than in the field. A more complete estimate of the survey completeness and false positive rate is needed to confirm these results. Light curves used in this work will be made available to the astronomical community on the Mikulski Archive for Space Telescope under the project PATHOS. △ Less

Submitted 25 May, 2020; originally announced May 2020.

Comments: 19 pages, 12 figures, 3 tables. Accepted for publication in MNRAS on May 20, 2020. PATHOS light curves are available at MAST as HLSP at https://archive.stsci.edu/hlsp/pathos

A PSF-based Approach to TESS High quality data Of Stellar clusters (PATHOS) -- I. Search for exoplanets and variable stars in the field of 47 Tuc

Authors: D. Nardiello, L. Borsato, G. Piotto, L. S. Colombo, E. E. Manthopoulou, L. R. Bedin, V. Granata, G. Lacedelli, M. Libralato, L. Malavolta, M. Montalto, V. Nascimbeni

Abstract: The TESS mission will survey ~85 % of the sky, giving us the opportunity of extracting high-precision light curves of millions of stars, including stellar cluster members. In this work, we present our project "A PSF-based Approach to TESS High quality data Of Stellar clusters" (PATHOS), aimed at searching and characterise candidate exoplanets and variable stars in stellar clusters using our innova… ▽ More The TESS mission will survey ~85 % of the sky, giving us the opportunity of extracting high-precision light curves of millions of stars, including stellar cluster members. In this work, we present our project "A PSF-based Approach to TESS High quality data Of Stellar clusters" (PATHOS), aimed at searching and characterise candidate exoplanets and variable stars in stellar clusters using our innovative method for the extraction of high-precision light curves of stars located in crowded environments. Our technique of light-curve extraction involves the use of empirical Point Spread Functions (PSFs), an input catalogue and neighbour-subtraction. The PSF-based approach allows us to minimise the dilution effects in crowded environments and to extract high-precision photometry for stars in the faint regime (G>13). For this pilot project, we extracted, corrected, and analysed the light curves of 16641 stars located in a dense region centred on the globular cluster 47 Tuc. We were able to reach the TESS magnitude T~16.5 with a photometric precision of ~1 % on the 6.5-hour timescale; in the bright regime we were able to detect transits with depth of ~34 parts per million. We searched for variables and candidate transiting exoplanets. Our pipeline detected one planetary candidate orbiting a main sequence star in the Galactic field. We analysed the period-luminosity distribution for red-giant stars of 47 Tuc and the eclipsing binaries in the field. Light curves are uploaded on the Mikulski Archive for Space Telescopes under the project PATHOS. △ Less

Submitted 8 October, 2019; originally announced October 2019.

Comments: 19 pages, 15 figures (3 at low resolution), 3 tables. Accepted for publication in MNRAS on October 4, 2019. PATHOS data products are available at MAST as HLSP at http://archive.stsci.edu/hlsp/pathos/

The Metallicity-Period-Mass Diagram of low-mass exoplanets

Authors: S. G. Sousa, V. Adibekyan, N. C. Santos, A. Mortier, S. C. C. Barros, E. Delgado-Mena, O. Demangeon, G. Israelian, J. P. Faria, P. Figueira, B. Rojas-Ayala, M. Tsantaki, D. T. Andreasen, I. Brandao, A. C. S. Ferreira, M. Montalto, A. Santerne

Abstract: The number of exoplanet detections continues to grow following the development of better instruments and missions. Key steps for the understanding of these worlds comes from their characterization and its statistical studies. We explore the metallicity-period-mass diagram for known exoplanets by using an updated version of The Stellar parameters for stars With ExoplanETs CATalog (SWEET-Cat), a uni… ▽ More The number of exoplanet detections continues to grow following the development of better instruments and missions. Key steps for the understanding of these worlds comes from their characterization and its statistical studies. We explore the metallicity-period-mass diagram for known exoplanets by using an updated version of The Stellar parameters for stars With ExoplanETs CATalog (SWEET-Cat), a unique compilation of precise stellar parameters for planet-host stars provided for the exoplanet community. Here we focus on the planets with minimum mass below 30 M$_{\oplus}$ which seems to present a possible correlation in the metallicity-period-mass diagram where the mass of the planet increases with both metallicity and period. Our analysis suggests that the general observed correlation may be not fully explained by observational biases. Additional precise data will be fundamental to confirm or deny this possible correlation. △ Less

Submitted 12 March, 2019; originally announced March 2019.

Comments: 12 pages, 9 Figures, Accepted for MNRAS

Ruprecht 147: a paradigm of dissolving star cluster

Authors: Fu-Chi Yeh, Giovanni Carraro, Marco Montalto, Anton F. Seleznev

Abstract: We employed recent Gaia/DR2 data to investigate the dynamical status of the nearby (300 pc), old (2.5 Gyr) open cluster Ruprecht~147. We found prominent leading and trailing tails of stars along the cluster orbit, which demonstrates that Ruprecht~147 is losing stars at fast pace. Star counts indicate the cluster has a core radius of 33.3 arcmin, and a tidal radius of 137.5 arcmin. The cluster also… ▽ More We employed recent Gaia/DR2 data to investigate the dynamical status of the nearby (300 pc), old (2.5 Gyr) open cluster Ruprecht~147. We found prominent leading and trailing tails of stars along the cluster orbit, which demonstrates that Ruprecht~147 is losing stars at fast pace. Star counts indicate the cluster has a core radius of 33.3 arcmin, and a tidal radius of 137.5 arcmin. The cluster also possesses an extended corona, which cannot be reproduced by a simple King model. We computed the present-day cluster mass using its luminosity and mass function, and derived an estimate of 234$\pm$52 $M_{\odot}$. We also estimated the cluster original mass using available recipes extracted from N-body simulations obtaining a mass at birth of 50000$\pm$6500 $M_{\odot}$. Therefore dynamical mass loss, mostly caused by tidal interaction with the Milky Way, reduced the cluster mass by about 99\%. We then conclude that Ruprecht~147 is rapidly dissolving into the general Galactic disc. △ Less

Submitted 14 January, 2019; originally announced January 2019.

Comments: 13 pages, 10 figure, in press in the Astronomical Journal

SWEET-Cat updated. New homogenous spectroscopic parameters

Authors: S. G. Sousa, V. Adibekyan, E. Delgado-Mena, N. C. Santos, D. T. Andreasen, A. C. S. Ferreira, M. Tsantaki, S. C. C. Barros, O. Demangeon, G. Israelian, J. P. Faria, P. Figueira, A. Mortier, I. Brandao, M. Montalto, B. Rojas-Ayala, A. Santerne

Abstract: Context: Exoplanets have now been proven to be very common. The number of its detections continues to grow following the development of better instruments and missions. One key step for the understanding of these worlds is their characterization, which mostly depend on their host stars. Aims:We perform a significant update of the Stars With ExoplanETs CATalog (SWEET-Cat), a unique compilation of p… ▽ More Context: Exoplanets have now been proven to be very common. The number of its detections continues to grow following the development of better instruments and missions. One key step for the understanding of these worlds is their characterization, which mostly depend on their host stars. Aims:We perform a significant update of the Stars With ExoplanETs CATalog (SWEET-Cat), a unique compilation of precise stellar parameters for planet-host stars provided for the exoplanet community. Methods: We made use of high-resolution spectra for planet-host stars, either observed by our team or found in several public archives. The new spectroscopic parameters were derived for the spectra following the same homogeneous process (ARES+MOOG). The host star parameters were then merged together with the planet properties listed in exoplanet.eu to perform simple data analysis. Results: We present new spectroscopic homogeneous parameters for 106 planet-host stars. Sixty-three planet hosts are also reviewed with new parameters. We also show that there is a good agreement between stellar parameters derived for the same star but using spectra obtained from different spectrographs. The planet-metallicity correlation is reviewed showing that the metallicity distribution of stars hosting low-mass planets (below 30 M$_{\oplus}$) is indistinguishable from that from the solar neighborhood sample in terms of metallicity distribution. △ Less

Submitted 18 October, 2018; originally announced October 2018.

Comments: 13 pages, 4 figures, 3 tables. accepted for A&A; Updated sweet-cat: https://www.astro.up.pt/resources/sweet-cat/

Journal ref: A&A 620, A58 (2018)

Planets around evolved intermediate-mass stars in open clusters II. Are there really planets around IC4651No9122, NGC2423No3 and NGC4349No127?

Authors: E. Delgado Mena, C. Lovis, N. C. Santos, J. Gomes da Silva, A. Mortier, M. Tsantaki, S. G. Sousa, P. Figueira, M. S. Cunha, T. L. Campante, V. Adibekyan, J. P. Faria, M. Montalto

Abstract: (shorter version)The aim of this work is to search for planets around intermediate-mass stars in open clusters by using RV data obtained with HARPS from an extensive survey with more than 15 years of observations for a sample of 142 giant stars in 17 open clusters. We present the discovery of a periodic RV signal compatible with the presence of a planet candidate in the 1.15 Gyr open cluster IC465… ▽ More (shorter version)The aim of this work is to search for planets around intermediate-mass stars in open clusters by using RV data obtained with HARPS from an extensive survey with more than 15 years of observations for a sample of 142 giant stars in 17 open clusters. We present the discovery of a periodic RV signal compatible with the presence of a planet candidate in the 1.15 Gyr open cluster IC4651 orbiting the 2.06 M$_\odot$ star No. 9122. If confirmed, the planet candidate would have a minimum mass of 7.2 M$_{J}$ and a period of 747 days. However, we also find that the FWHM of the CCF varies with a period close to the RV, casting doubts on the planetary nature of the signal. We also provide refined parameters for the previously discovered planet around NGC2423 No. 3 but show evidence that the BIS of the CCF is correlated with the RV during some of the observing periods. This fact advises us that this might not be a real planet and that the RV variations could be caused by stellar activity and/or pulsations. Finally, we show that the previously reported signal by a brown dwarf around NGC4349 No. 127 is presumably produced by stellar activity modulation. The long-term monitoring of several red giants in open clusters has allowed us to find periodic RV variations in several stars. However, we also show that the follow-up of this kind of stars should last more than one orbital period to detect long-term signals of stellar origin. This work warns that although it is possible to detect planets around red giants, large-amplitude, long-period RV modulations do exist in such stars that can mimic the presence of an orbiting planetary body. Therefore, we need to better understand how such RV modulations behave as stars evolve along the RGB and perform a detailed study of all the possible stellar-induced signals (e.g. spots, pulsations, granulation) to comprehend the origin of RV variations. △ Less

Submitted 25 July, 2018; originally announced July 2018.

Comments: 15 pages, 18 figures, accepted by A&A

Journal ref: A&A 619, A2 (2018)

Disentangling planetary and stellar activity features in the CoRoT-2 light curve

Authors: G. Bruno, M. Deleuil, J. -M. Almenara, S. C. C. Barros, A. F. Lanza, M. Montalto, I. Boisse, A. Santerne, A. -M. Lagrange, N. Meunier

Abstract: [Abridged] Context. Stellar activity is an important source of systematic errors and uncertainties in the characterization of exoplanets. Most of the techniques used to correct for this activity focus on an ad hoc data reduction. Aims. We have developed a software for the combined fit of transits and stellar activity features in high-precision long-duration photometry. Our aim is to take advantage… ▽ More [Abridged] Context. Stellar activity is an important source of systematic errors and uncertainties in the characterization of exoplanets. Most of the techniques used to correct for this activity focus on an ad hoc data reduction. Aims. We have developed a software for the combined fit of transits and stellar activity features in high-precision long-duration photometry. Our aim is to take advantage of the modelling to derive correct stellar and planetary parameters, even in the case of strong stellar activity. Methods. We use an analytic approach to model the light curve. The code KSint, modified by adding the evolution of active regions, is implemented into our Bayesian modelling package PASTIS. The code is then applied to the light curve of CoRoT-2. The light curve is divided in segments to reduce the number of free parameters needed by the fit. We perform a Markov chain Monte Carlo analysis in two ways. In the first, we perform a global and independent modelling of each segment of the light curve, transits are not normalized and are fitted together with the activity features, and occulted features are taken into account during the transit fit. In the second, we normalize the transits with a model of the non-occulted activity features, and then we apply a standard transit fit, which does not take the occulted features into account. Results. Our model recovers the activity features coverage of the stellar surface and different rotation periods for different features. We find variations in the transit parameters of different segments and show that they are likely due to the division applied to the light curve. Neglecting stellar activity or even only bright spots while normalizing the transits yields a $\sim 1.2σ$ larger and $2.3σ$ smaller transit depth, respectively. The stellar density also presents up to $2.5σ$ differences depending on the normalization technique... △ Less

Submitted 5 August, 2016; originally announced August 2016.

Comments: 14 pages, 7 figures, 6 tables, accepted on A&A. arXiv admin note: text overlap with arXiv:1604.03979

Journal ref: A&A 595, A89 (2016)

Photometry of Centaurs and trans-Neptunian objects: 2060 Chiron (1977 UB), 10199 Chariklo (1997 CU26), 38628 Huya (2000 EB173), 28978 Ixion (2001 KX76), and 90482 Orcus (2004 DW)

Authors: Mattia Galiazzo, Carlos de la Fuente Marcos, Raul de la Fuente Marcos, Giovanni Carraro, Michele Maris, Marco Montalto

Abstract: Both Centaurs and trans-Neptunian objects (TNOs) are minor bodies found in the outer Solar System. Centaurs are a transient population that moves between the orbits of Jupiter and Neptune, and they probably diffused out of the TNOs. TNOs move mainly beyond Neptune. Some of these objects display episodic cometary behaviour; a few percent of them are known to host binary companions. Here, we study t… ▽ More Both Centaurs and trans-Neptunian objects (TNOs) are minor bodies found in the outer Solar System. Centaurs are a transient population that moves between the orbits of Jupiter and Neptune, and they probably diffused out of the TNOs. TNOs move mainly beyond Neptune. Some of these objects display episodic cometary behaviour; a few percent of them are known to host binary companions. Here, we study the light-curves of two Centaurs -2060 Chiron (1977 UB) and 10199 Chariklo (1997 CU26)- and three TNOs -38628 Huya (2000 EB173), 28978 Ixion (2001 KX76), and 90482 Orcus (2004 DW)- and the colours of the Centaurs and Huya. Precise, ~1%, R-band absolute CCD photometry of these minor bodies acquired between 2006 and 2011 is presented; the new data are used to investigate the rotation rate of these objects. The colours of the Centaurs and Huya are determined using BVRI photometry. The point spread function of the five minor bodies is analysed, searching for signs of a coma or close companions. Astrometry is also discussed. A periodogram analysis of the light-curves of these objects gives the following rotational periods: 5.5+-0.4 h for Chiron, 7.0+-0.6 h for Chariklo, 4.45+-0.07 h for Huya, 12.4+-0.3 h for Ixion, and 11.9+-0.5 h for Orcus. The colour indices of Chiron are found to be B-V=0.53+-0.05, V-R=0.37+-0.08, and R-I=0.36+-0.15. The values computed for Chariklo are V-R=0.62+-0.07 and R-I=0.61+-0.07. For Huya, we find V-R=0.58+-0.09 and R-I=0.64+-0.20. We find very low levels of cometary activity (if any) and no sign of close or wide binary companions for these minor bodies. △ Less

Submitted 3 June, 2016; v1 submitted 26 May, 2016; originally announced May 2016.

Comments: 21 pages, 6 figures, 8 tables + 10 tables in one appendix, accepted for publication in Astrophysics and Space Science (slightly abridged abstract to comply with size limits)

An extreme planetary system around HD219828. One long-period super Jupiter to a hot-neptune host star

Authors: N. C. Santos, A. Santerne, J. P. Faria, J. Rey, A. C. M. Correia, J. Laskar, S. Udry, V. Adibekyan, F. Bouchy, E. Delgado-Mena, C. Melo, X. Dumusque, G. Hébrard, C. Lovis, M. Mayor, M. Montalto, A. Mortier, F. Pepe, P. Figueira, J. Sahlmann, D. Ségransan, S. G. Sousa

Abstract: With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. We present a full investigation of the HD219828 system, a bright metal-rich star for which a hot neptune has previously been detected. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD219828. A dynamic… ▽ More With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. We present a full investigation of the HD219828 system, a bright metal-rich star for which a hot neptune has previously been detected. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD219828. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. We announce the discovery of a long period (P=13.1years) massive (msini=15.1MJup) companion (HD219828c) in a very eccentric orbit (e=0.81). The same data confirms the existence of a hot-neptune, HD219828b, with a minimum mass of 21 MEarth and a period of 3.83days. The dynamical analysis shows that the system is stable. The HD219828 system is extreme and unique in several aspects. First, among all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD219828, with a hot neptune and a long-period massive companion are more frequent than similar systems with a hot jupiter instead. This suggests that the formation of hot neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD219828c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD219828b is detected, we will be able to fully characterise the system, including the relative orbital inclinations. With a clearly known mass, HD219828c may become a benchmark object for the range in between giant planets and brown dwarfs. △ Less

Submitted 23 May, 2016; originally announced May 2016.

Comments: Astronomy & Astrophysics, in press

Journal ref: A&A 592, A13 (2016)

EPIC211089792 b: an aligned and inflated hot jupiter in a young visual binary

Authors: A. Santerne, G. Hébrard, J. Lillo-Box, D. J. Armstrong, S. C. C. Barros, O. Demangeon, D. Barrado, A. Debackere, M. Deleuil, E. Delgado Mena, M. Montalto, D. Pollacco, H. P. Osborn, S. G. Sousa, L. Abe, V. Adibekyan, J. -M. Almenara, P. André, G. Arlic, G. Barthe, P. Bendjoya, R. Behrend, I. Boisse, F. Bouchy, H. Boussier , et al. (49 additional authors not shown)

Abstract: In the present paper we report the discovery of a new hot Jupiter, EPIC211089792 b, first detected by the Super-WASP observatory and then by the K2 space mission during its campaign 4. The planet has a period of 3.25d, a mass of 0.73 +/- 0.04 Mjup, and a radius of 1.19 +/- 0.02 Rjup. The host star is a relatively bright (V=12.5) G7 dwarf with a nearby K5V companion. Based on stellar rotation and t… ▽ More In the present paper we report the discovery of a new hot Jupiter, EPIC211089792 b, first detected by the Super-WASP observatory and then by the K2 space mission during its campaign 4. The planet has a period of 3.25d, a mass of 0.73 +/- 0.04 Mjup, and a radius of 1.19 +/- 0.02 Rjup. The host star is a relatively bright (V=12.5) G7 dwarf with a nearby K5V companion. Based on stellar rotation and the abundance of Lithium, we find that the system might be as young as about 450 Myr. The observation of the Rossiter-McLaughlin effect shows the planet is aligned with respect to the stellar spin. Given the deep transit (20mmag), the magnitude of the star and the presence of a nearby stellar companion, the planet is a good target for both space- and ground-based transmission spectroscopy, in particular in the near-infrared where the both stars are relatively bright. △ Less

Submitted 28 January, 2016; originally announced January 2016.

Comments: Submitted to ApJ

Journal ref: 2016, ApJ, 825, 55

An extensive radial velocity survey toward NGC 6253

Authors: M. Montalto, C. H. F. Melo, N. C. Santos, D. Queloz, G. Piotto, S. Desidera, L. R. Bedin, Y. Momany, I. Saviane

Abstract: The old and metal rich open cluster NGC 6253 was observed with the FLAMES multi-object spectrograph during an extensive radial velocity campaign monitoring 317 stars with a median of 15 epochs per object. All the targeted stars are located along the upper main sequence of the cluster between 14.8 $<$ V $<$ 16.5. Fifty nine stars are confirmed cluster members both by radial velocities and proper mo… ▽ More The old and metal rich open cluster NGC 6253 was observed with the FLAMES multi-object spectrograph during an extensive radial velocity campaign monitoring 317 stars with a median of 15 epochs per object. All the targeted stars are located along the upper main sequence of the cluster between 14.8 $<$ V $<$ 16.5. Fifty nine stars are confirmed cluster members both by radial velocities and proper motions and do not show evidence of variability. We detected 45 variable stars among which 25 belong to NGC 6253. We were able to derive an orbital solution for 4 cluster members (and for 2 field stars) yielding minimum masses in between $\sim$90 M$\rm_J$ and $\sim$460 M$\rm_J$ and periods between 3 and 220 days. Simulations demonstrated that this survey was sensitive to objects down to 30 M$\rm_J$ at 10 days orbital periods with a detection efficiency equal to 50%. On the basis of these results we concluded that the observed frequency of binaries down to the hydrogen burning limit and up to 20 days orbital period is around (1.5$\pm$1.3)% in NGC 6253. The overall observed frequency of binaries around the sample of cluster stars is (13$\pm$3)%. The median radial velocity precision achieved by the GIRAFFE spectrograph in this magnitude range was around $\sim$240m$\rm\,s^{-1}$ ($\sim$180 m$\rm\,s^{-1}$ for UVES). Based on a limited follow-up analysis of 7 stars in our sample with the HARPS spectrograph we determined that a precision of 35 m $\rm s^{-1}$ can be reached in this magnitude range, offering the possibility to further extend the variability analysis into the substellar domain. Prospects are even more favourable once considering the upcoming ESPRESSO spectrograph at VLT. △ Less

Submitted 10 January, 2016; originally announced January 2016.

Comments: Accepted by MNRAS

A hot horizontal branch star with a close K-type main-sequence companion

Authors: C. Moni Bidin, Y. Momany, M. Montalto, M. Catelan, S. Villanova, G. Piotto, D. Geisler

Abstract: Dynamical interactions in binary systems are thought to play a major role in the formation of extreme horizontal branch stars (EHBs) in the Galactic field. However, it is still unclear if the same mechanisms are at work in globular clusters, where EHBs are predominantly single stars. Here we report on the discovery of a unique close binary system (period ~1.61 days) in the globular cluster NGC6752… ▽ More Dynamical interactions in binary systems are thought to play a major role in the formation of extreme horizontal branch stars (EHBs) in the Galactic field. However, it is still unclear if the same mechanisms are at work in globular clusters, where EHBs are predominantly single stars. Here we report on the discovery of a unique close binary system (period ~1.61 days) in the globular cluster NGC6752, comprising an EHB and a main-sequence companion of 0.63+-0.05 Msun. Such a system has no counterpart among nearly two hundred known EHB binaries in the Galactic field. Its discovery suggests that either field studies are incomplete, missing this type of systems possibly because of selection effects, or that a particular EHB formation mechanism is active in clusters but not in the field. △ Less

Submitted 26 October, 2015; originally announced October 2015.

Detecting ring systems around exoplanets using high resolution spectroscopy: the case of 51Pegb

Authors: N. C. Santos, J. H. C. Martins, G. Boué, A. C. M. Correia, M. Oshagh, P. Figueira, A. Santerne, S. G. Sousa, C. Melo, M. Montalto, I. Boisse, D. Ehrenreich, C. Lovis, F. Pepe, S. Udry, A. Garcia Munoz

Abstract: In this paper we explore the possibility that the recently detected reflected light signal of 51\,Peg\,b could be caused by a ring system around the planet. We use a simple model to compare the observed signal with the expected signal from a short-period giant planet with rings. We also use simple dynamical arguments to understand the possible geometry of such a system. We provide evidence that, t… ▽ More In this paper we explore the possibility that the recently detected reflected light signal of 51\,Peg\,b could be caused by a ring system around the planet. We use a simple model to compare the observed signal with the expected signal from a short-period giant planet with rings. We also use simple dynamical arguments to understand the possible geometry of such a system. We provide evidence that, to a good approximation, the observations are compatible with the signal expected from a ringed planet, assuming that the rings are non-coplanar with the orbital plane. However, based on dynamical arguments, we also show that this configuration is unlikely. In the case of coplanar rings we then demonstrate that the incident flux on the ring surface is about 2\% the value received by the planet, a value that renders the ring explanation unlikely. The results suggest that the signal observed cannot in principle be explained by a planet+ring system. We discuss, however, the possibility of using reflected light spectra to detect and characterize the presence of rings around short-period planets. Finally, we show that ring systems could have already been detected by photometric transit campaigns, but their signal could have been easily misinterpreted by the expected light curve of an eclipsing binary. △ Less

Submitted 2 September, 2015; originally announced September 2015.

Comments: Astronomy & Astrophysics, in press

Further constraints on the optical transmission spectrum of HAT-P-1b

Authors: M. Montalto, N. Iro, N. C. Santos, S. Desidera, J. H. C. Martins, P. Figueira, R. Alonso, .

Abstract: We report on novel observations of HAT-P-1 aimed at constraining the optical transmission spectrum of the atmosphere of its transiting Hot-Jupiter exoplanet. Ground-based differential spectrophotometry was performed over two transit windows using the DOLORES spectrograph at the Telescopio Nazionale Galileo (TNG). Our measurements imply an average planet to star radius ratio equal to… ▽ More We report on novel observations of HAT-P-1 aimed at constraining the optical transmission spectrum of the atmosphere of its transiting Hot-Jupiter exoplanet. Ground-based differential spectrophotometry was performed over two transit windows using the DOLORES spectrograph at the Telescopio Nazionale Galileo (TNG). Our measurements imply an average planet to star radius ratio equal to $\rm R_p/R_{\star}$=(0.1159$\pm$0.0005). This result is consistent with the value obtained from recent near infrared measurements of this object but differs from previously reported optical measurements being lower by around 4.4 exoplanet scale heights. Analyzing the data over 5 different spectral bins 600Å$\,$ wide we observed a single peaked spectrum (3.7 $\rmσ$ level) with a blue cut-off corresponding to the blue edge of the broad absorption wing of sodium and an increased absorption in the region in between 6180-7400Å. We also infer that the width of the broad absorption wings due to alkali metals is likely narrower than the one implied by solar abundance clear atmospheric models. We interpret the result as evidence that HAT-P-1b has a partially clear atmosphere at optical wavelengths with a more modest contribution from an optical absorber than previously reported. △ Less

Submitted 26 August, 2015; originally announced August 2015.

Comments: Accepted by ApJ

Evidence for a spectroscopic direct detection of reflected light from 51 Peg b

Authors: J. H. C. Martins, N. C. Santos, P. Figueira, J. P. Faria, M. Montalto, I. Boisse, D. Ehrenreich, C. Lovis, M. Mayor, C. Melo, F. Pepe, S. G. Sousa, S. Udry, D. Cunha

Abstract: The detection of reflected light from an exoplanet is a difficult technical challenge at optical wavelengths. Even though this signal is expected to replicate the stellar signal, not only is it several orders of magnitude fainter, but it is also hidden among the stellar noise. We apply a variant of the cross-correlation technique to HARPS observations of 51 Peg to detect the reflected signal from… ▽ More The detection of reflected light from an exoplanet is a difficult technical challenge at optical wavelengths. Even though this signal is expected to replicate the stellar signal, not only is it several orders of magnitude fainter, but it is also hidden among the stellar noise. We apply a variant of the cross-correlation technique to HARPS observations of 51 Peg to detect the reflected signal from planet 51 Peg b. Our method makes use of the cross-correlation function of a binary mask with high-resolution spectra to amplify the minute planetary signal that is present in the spectra by a factor proportional to the number of spectral lines when performing the cross correlation. The resulting cross-correlation functions are then normalized by a stellar template to remove the stellar signal. Carefully selected sections of the resulting normalized CCFs are stacked to increase the planetary signal further. The recovered signal allows probing several of the planetary properties, including its real mass and albedo. We detect evidence for the reflected signal from planet 51 Peg b at a significance of 3σ_noise. The detection of the signal permits us to infer a real mass of 0.46^+0.06_-0.01 M_Jup (assuming a stellar mass of 1.04\;M_Sun) for the planet and an orbital inclination of 80^+10_-19 degrees. The analysis of the data also allows us to infer a tentative value for the (radius-dependent) geometric albedo of the planet. The results suggest that 51Peg b may be an inflated hot Jupiter with a high albedo (e.g., an albedo of 0.5 yields a radius of 1.9 \pm 0.3 R_Jup for a signal amplitude of 6.0\pm0.4 x 10^-5). We confirm that the method we perfected can be used to retrieve an exoplanet's reflected signal, even with current observing facilities. The advent of next generation of observing facilities will yield new opportunities for this type of technique to probe deeper into exoplanets. △ Less

Submitted 22 April, 2015; originally announced April 2015.

Comments: 9 pages, 6 figures

Journal ref: A&A, Volume 576, April 2015, A134

The EChO science case

Authors: Giovanna Tinetti, Pierre Drossart, Paul Eccleston, Paul Hartogh, Kate Isaak, Martin Linder, Christophe Lovis, Giusi Micela, Marc Ollivier, Ludovic Puig, Ignasi Ribas, Ignas Snellen, Bruce Swinyard. France Allard, Joanna Barstow, James Cho, Athena Coustenis, Charles Cockell, Alexandre Correia, Leen Decin, Remco de Kok, Pieter Deroo, Therese Encrenaz, Francois Forget, Alistair Glasse, Caitlin Griffith , et al. (326 additional authors not shown)

Abstract: The discovery of almost 2000 exoplanets has revealed an unexpectedly diverse planet population. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? What causes the exceptional divers… ▽ More The discovery of almost 2000 exoplanets has revealed an unexpectedly diverse planet population. Observations to date have shown that our Solar System is certainly not representative of the general population of planets in our Milky Way. The key science questions that urgently need addressing are therefore: What are exoplanets made of? Why are planets as they are? What causes the exceptional diversity observed as compared to the Solar System? EChO (Exoplanet Characterisation Observatory) has been designed as a dedicated survey mission for transit and eclipse spectroscopy capable of observing a large and diverse planet sample within its four-year mission lifetime. EChO can target the atmospheres of super-Earths, Neptune-like, and Jupiter-like planets, in the very hot to temperate zones (planet temperatures of 300K-3000K) of F to M-type host stars. Over the next ten years, several new ground- and space-based transit surveys will come on-line (e.g. NGTS, CHEOPS, TESS, PLATO), which will specifically focus on finding bright, nearby systems. The current rapid rate of discovery would allow the target list to be further optimised in the years prior to EChO's launch and enable the atmospheric characterisation of hundreds of planets. Placing the satellite at L2 provides a cold and stable thermal environment, as well as a large field of regard to allow efficient time-critical observation of targets randomly distributed over the sky. A 1m class telescope is sufficiently large to achieve the necessary spectro-photometric precision. The spectral coverage (0.5-11 micron, goal 16 micron) and SNR to be achieved by EChO, thanks to its high stability and dedicated design, would enable a very accurate measurement of the atmospheric composition and structure of hundreds of exoplanets. △ Less

Submitted 19 February, 2015; originally announced February 2015.

Comments: 50 pages, 30 figures. Experimental Astronomy

On the HI-Hole and AGB Stellar Population of the Sagittarius Dwarf Irregular Galaxy

Authors: Y. Momany, M. Clemens, L. R. Bedin, M. Gullieuszik, E. V. Held, I. Saviane, S. Zaggia, L. Monaco, M. Montalto, R. M. Rich, L. Rizzi

Abstract: Using two HST/ACS data-sets that are separated by ~2 years has allowed us to derive the relative proper-motion for the Sagittarius dwarf irregular (SagDIG) and reduce the heavy foreground Galactic contamination. The proper-motion decontaminated SagDIG catalog provides a much clearer view of the young red-supergiant and intermediate-age asymptotic giant branch populations. We report the identificat… ▽ More Using two HST/ACS data-sets that are separated by ~2 years has allowed us to derive the relative proper-motion for the Sagittarius dwarf irregular (SagDIG) and reduce the heavy foreground Galactic contamination. The proper-motion decontaminated SagDIG catalog provides a much clearer view of the young red-supergiant and intermediate-age asymptotic giant branch populations. We report the identification of 3 Milky Way carbon-rich dwarf stars, probably belonging to the thin disk, and pointing to the high incidence of this class at low Galactic latitudes. A sub-group of 4 oxygen-rich candidate stars depicts a faint, red extension of the well-defined SagDIG carbon-rich sequence. The origin of these oxygen-rich candidate stars remains unclear, reflecting the uncertainty in the ratio of carbon/oxygen rich stars. SagDIG is also a gas-rich galaxy characterized by a single large cavity in the gas disk (HI-hole), which is offset by ~360 pc from the optical centre of the galaxy. We nonetheless investigate the stellar feedback hypothesis by comparing the proper-motion cleaned stellar populations within the HI-hole with appropriately selected comparison regions, having higher HI densities external to the hole. The comparison shows no significant differences. In particular, the centre of the HI-hole (and the comparison regions) lack stellar populations younger than ~400 Myr, which are otherwise abundant in the inner body of the galaxy. We conclude that there is no convincing evidence that the SagDIG HI-hole is the result of stellar feedback, and that gravitational and thermal instabilities in the gas are the most likely mechanism for its formation. △ Less

Submitted 25 August, 2014; originally announced August 2014.

Comments: Accepted for publication in A&A, 11 pages, 6 jpeg figures

Journal ref: A&A 572, A42 (2014)

Spectroscopic parameters for solar-type stars with moderate/high rotation. New parameters for 10 planet-hosts

Authors: M. Tsantaki, S. G. Sousa, N. C. Santos, M. Montalto, E. Delgado-Mena, A. Mortier, V. Adibekyan, G. Israelian

Abstract: Planetary studies demand precise and accurate stellar parameters as input to infer the planetary properties. Different methods often provide different results that could lead to biases in the planetary parameters. In this work, we present a refinement of the spectral synthesis technique designed to treat better more rapidly rotating FGK stars. This method is used to derive precise stellar paramete… ▽ More Planetary studies demand precise and accurate stellar parameters as input to infer the planetary properties. Different methods often provide different results that could lead to biases in the planetary parameters. In this work, we present a refinement of the spectral synthesis technique designed to treat better more rapidly rotating FGK stars. This method is used to derive precise stellar parameters, namely effective temperature, surface gravity, metallicitity and rotational velocity. This procedure is tested for samples of low and moderate/fast rotating FGK stars. The spectroscopic analysis is based on the spectral synthesis package Spectroscopy Made Easy (SME), assuming Kurucz model atmospheres in LTE. The line list where the synthesis is conducted, is comprised of iron lines and the atomic data are derived after solar calibration. The comparison of our stellar parameters shows good agreement with literature values, both for low and for higher rotating stars. In addition, our results are on the same scale with the parameters derived from the iron ionization and excitation method presented in our previous works. We present new atmospheric parameters for 10 transiting planet-hosts as an update to the SWEET-Cat catalogue. We also re-analyse their transit light curves to derive new updated planetary properties. △ Less

Submitted 24 July, 2014; originally announced July 2014.

Comments: 14 pages, Accepted in A&A

Journal ref: A&A 570, A80 (2014)

Improvements on analytic modelling of stellar spots

Authors: M. Montalto, G. Boué, M. Oshagh, I. Boisse, G. Bruno, N. C. Santos

Abstract: In this work we present the solution of the stellar spot problem using the Kelvin-Stokes theorem. Our result is applicable for any given location and dimension of the spots on the stellar surface. We present explicitely the result up to the second degree in the limb darkening law. This technique can be used to calculate very efficiently mutual photometric effects produced by eclipsing bodies occul… ▽ More In this work we present the solution of the stellar spot problem using the Kelvin-Stokes theorem. Our result is applicable for any given location and dimension of the spots on the stellar surface. We present explicitely the result up to the second degree in the limb darkening law. This technique can be used to calculate very efficiently mutual photometric effects produced by eclipsing bodies occulting stellar spots and to construct complex spot shapes. △ Less

Submitted 8 July, 2014; originally announced July 2014.

Comments: Resubmitted to MNRAS after accounting for minor comments of second review, 9 pages, 5 figures, software available at http://eduscisoft.com/KSINT/

Impact of occultations of stellar active regions on transmission spectra: Can occultation of a plage mimic the signature of a blue sky?

Authors: M. Oshagh, N. C. Santos, D. Ehrenreich, N. Haghighipour, P. Figueira, A. Santerne, M. Montalto

Abstract: Transmission spectroscopy during planetary transits, which is based on the measurements of the variations of planet-to-star radius ratio as a function of wavelength, is a powerful technique to study the atmospheric properties of transiting planets. One of the main limitation of this technique is the effects of stellar activity, which up until now, have been taken into account only by assessing the… ▽ More Transmission spectroscopy during planetary transits, which is based on the measurements of the variations of planet-to-star radius ratio as a function of wavelength, is a powerful technique to study the atmospheric properties of transiting planets. One of the main limitation of this technique is the effects of stellar activity, which up until now, have been taken into account only by assessing the effect of non-occulted stellar spots on the estimates of planet-to-star radius ratio. In this paper, we study, for the first time, the impact of the occultation of a stellar spot and plage on the transmission spectra of transiting exoplanets. We simulated this effect by generating a large number of transit light curves for different transiting planets, stellar spectral types, and for different wavelengths. Results of our simulations indicate that the anomalies inside the transit light curve can lead to a significant underestimation or overestimation of the planet-to-star radius ratio as a function of wavelength. At short wavelengths, the effect can reach to a difference of up to 10% in the planet-to-star radius ratio, mimicking the signature of light scattering in the planetary atmosphere. Atmospheric scattering has been proposed to interpret the increasing slopes of transmission spectra toward blue for exoplanets HD 189733b and GJ 3470b. Here we show that these signatures can be alternatively interpreted by the occultation of stellar plages. Results also suggest that the best strategy to identify and quantify the effects of stellar activities on the transmission spectrum of a planet is to perform several observations during the transit epoch at the same wavelength. This will allow for identifying the possible variations in transit depth as a function of time due to stellar activity variability. △ Less

Submitted 8 July, 2014; originally announced July 2014.

Comments: 7 pages, 6 figures, Accepted for publication in A&A

Journal ref: A&A 568, A99 (2014)

The SOPHIE search for northern extrasolar planets: VI. Three new hot Jupiters in multi-planet extrasolar systems

Authors: C. Moutou, G. Hebrard, F. Bouchy, L. Arnold, N. C. Santos, N. Astudillo-Defru, I. Boisse, X. Bonfils, S. Borgniet, X. Delfosse, R. F. Diaz, D. Ehrenreich, T. Forveille, J. Gregorio, O. Labrevoir, A. M. Lagrange, G. Montagnier, M. Montalto, F. Pepe, J. Sahlmann, A. Santerne, D. Segransan, S. Udry, M. Vanhuysse

Abstract: We present high-precision radial-velocity measurements of three solar-type stars: HD 13908, HD 159243, and HIP 91258. The observations were made with the SOPHIE spectrograph at the 1.93-m telescope of Observatoire de Haute-Provence (France). They show that these three bright stars host exoplanetary systems composed of at least two companions. HD 13908 b is a planet with a minimum mass of 0.865+-0.… ▽ More We present high-precision radial-velocity measurements of three solar-type stars: HD 13908, HD 159243, and HIP 91258. The observations were made with the SOPHIE spectrograph at the 1.93-m telescope of Observatoire de Haute-Provence (France). They show that these three bright stars host exoplanetary systems composed of at least two companions. HD 13908 b is a planet with a minimum mass of 0.865+-0.035 Mjup, on a circular orbit with a period of 19.382+-0.006 days. There is an outer massive companion in the system with a period of 931+-17 days, e = 0.12+-0.02, and a minimum mass of 5.13+-0.25 Mjup. The star HD 159243, also has two detected companions with respective masses, periods, and eccentricities of Mp = 1.13+-0.05 and 1.9+-0.13 Mjup, $P$ = 12.620+-0.004 and 248.4+-4.9 days, and e = 0.02+-0.02 and 0.075+-0.05. Finally, the star HIP 91258 has a planetary companion with a minimum mass of 1.068+-0.038 Mjup, an orbital period of 5.0505+-0.0015 days, and a quadratic trend indicating an outer planetary or stellar companion that is as yet uncharacterized. The planet-hosting stars HD 13908, HD 159243, and HIP 91258 are main-sequence stars of spectral types F8V, G0V, and G5V, respectively, with moderate activity levels. HIP 91258 is slightly over-metallic, while the two other stars have solar-like metallicity. The three systems are discussed in the frame of formation and dynamical evolution models of systems composed of several giant planets. △ Less

Submitted 20 November, 2013; originally announced November 2013.

Comments: accepted in A&A

The PLATO 2.0 Mission

Authors: H. Rauer, C. Catala, C. Aerts, T. Appourchaux, W. Benz, A. Brandeker, J. Christensen-Dalsgaard, M. Deleuil, L. Gizon, M. -J. Goupil, M. Güdel, E. Janot-Pacheco, M. Mas-Hesse, I. Pagano, G. Piotto, D. Pollacco, N. C. Santos, A. Smith, J. -C., Suárez, R. Szabó, S. Udry, V. Adibekyan, Y. Alibert, J. -M. Almenara , et al. (137 additional authors not shown)

Abstract: PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small ap… ▽ More PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 sec readout cadence and 2 with 2.5 sec candence) providing a wide field-of-view (2232 deg2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2%, 4-10% and 10% for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50% of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. △ Less

Submitted 4 March, 2014; v1 submitted 2 October, 2013; originally announced October 2013.

Comments: 63 pages, 17 figures, submitted to Experimental Astronomy (ExA)