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Planet-Host Stars Across the Galaxy in the 2040s
Authors:
M. Tsantaki,
K. Biazzo,
F. Zahra Majidi,
G. Tautvaisiene,
I. Busa
Abstract:
By the 2040s, the exoplanet field will have moved from the discovery of a few thousand planets to hundreds of thousands, thanks to Gaia DR5, TESS, PLATO, Roman, and their successors. At that stage, the key bottleneck will no longer be planet detection, but our ability to understand how planetary systems form, evolve, and diversify across different stellar and Galactic environments.
To address th…
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By the 2040s, the exoplanet field will have moved from the discovery of a few thousand planets to hundreds of thousands, thanks to Gaia DR5, TESS, PLATO, Roman, and their successors. At that stage, the key bottleneck will no longer be planet detection, but our ability to understand how planetary systems form, evolve, and diversify across different stellar and Galactic environments.
To address this, we need a large-scale, high-resolution spectroscopic survey of planet-host stars, spanning a broad range of Galactic environments (thin and thick disks, bulge, halo, clusters, associations), and including a well-defined control sample of non-hosts. Such a survey must deliver homogeneous stellar parameters, detailed abundance determinations, ages, and kinematics for tens of thousands of hosts, extending to the faint magnitudes probed by future missions but are beyond the reach of existing and currently planned spectroscopic facilities.
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Submitted 13 January, 2026;
originally announced January 2026.
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Standard Sirens in 2040s: Probing the Cosmic Expansion History with Gravitational Waves and Spectroscopic Galaxy Surveys
Authors:
Nicola Borghi,
Michele Moresco,
Richard I. Anderson,
Carmelita Carbone,
Andrea Cimatti,
Stephanie Escoffier,
Carlo Giocoli,
Sean MacBride,
Fatemeh Zahra Majidi,
Dinko Milaković,
Lauro Moscardini,
Lucia Pozzetti,
Margherita Talia,
Elena Tomasetti
Abstract:
Gravitational waves (GWs) from compact binary coalescences have matured into a robust cosmological probe, providing self-calibrated luminosity distance measurements independent of any cosmic distance ladder, hence the term "standard sirens". The binary neutron star merger GW170817 delivered the first such measurement of the Hubble constant, demonstrating that GWs offer a path to precision cosmolog…
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Gravitational waves (GWs) from compact binary coalescences have matured into a robust cosmological probe, providing self-calibrated luminosity distance measurements independent of any cosmic distance ladder, hence the term "standard sirens". The binary neutron star merger GW170817 delivered the first such measurement of the Hubble constant, demonstrating that GWs offer a path to precision cosmology with systematics orthogonal to standard cosmological probes. To convert GW distances into cosmological parameters, redshift information is essential. To maximize the scientific potential, the redshift must be obtained from individual galaxies, either by identifying electromagnetic counterparts of GW events (bright sirens) or by statistically associating potential hosts within the GW localization volume (dark sirens). The precision of these redshifts sets the achievable accuracy. Forecasts show that photometric uncertainties degrade cosmological constraints by up to an order of magnitude compared to spectroscopic ones. Wide-field, high-multiplex spectroscopic facilities will therefore be an essential infrastructure for GW cosmology in the 2040s.
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Submitted 20 December, 2025;
originally announced December 2025.
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Designing the Community Infrastructure for ESO's Next Transformational Facility. Equitable Governance and Sustainable Teams for 2040s Astronomy
Authors:
Annagrazia Puglisi,
Amelia Bayo,
Laurane Freour,
Daniela Iglesias,
Akhil Krishna,
Fatemeh Zahra Majidi,
Umberto Rescigno,
Sabine Thater,
Laurence Tresse,
Tanya Urrutia
Abstract:
The scientific ambitions of the 2040s will require large, interdisciplinary teams operating across continents, institutions, and increasingly heterogeneous political and funding landscapes. While significant effort is devoted to advancing the technical capabilities of future astronomical facilities, frameworks for coordinating and sustaining the associated community systems are often developed in…
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The scientific ambitions of the 2040s will require large, interdisciplinary teams operating across continents, institutions, and increasingly heterogeneous political and funding landscapes. While significant effort is devoted to advancing the technical capabilities of future astronomical facilities, frameworks for coordinating and sustaining the associated community systems are often developed in parallel rather than embedded as coherent, long-term structures at the scale needed to fully realise this ambition. In this white paper, submitted as part of the ESO Expanding Horizons initiative, we draw on experience from established observatories and emerging collaborations to identify key community-level challenges. We argue that a central and transversal scientific challenge for the 2040s is to operate a flagship observatory in which access to telescope time, data, leadership, training, and career development is equitable across institutions, member states, and beyond. We propose that access and participation be treated as integral design parameters, embedded from the conceptual stage and sustained throughout the facility lifecycle, in order to ensure long-term scientific excellence, sustainability, and societal return.
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Submitted 19 December, 2025;
originally announced December 2025.
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Spectroscopic Alerts for the Time-Domain Era
Authors:
Alejandra Melo,
Paula Sanchez-Saez,
Valentin D. Ivanov,
Richard I. Anderson,
Amelia Bayo,
Avraham Binnenfeld,
Sofia Bisero,
Dragana Ilić,
Andjelka B. Kovačević,
Fatemeh Zahra Majidi,
Jaroslav Merc,
Anna Pala,
Swayamtrupta Panda,
Sarath Satheesh-Sheeba,
Fabian Schüssler,
Susanna D. Vergani
Abstract:
Time-domain astronomy is entering an era of unprecedented discovery driven by wide-field, high-cadence surveys such as LSST, Roman, Euclid, SKA, and PLATO. While some of these facilities will generate enormous photometric alert streams, the physical interpretation of variability and transients often requires spectroscopy, which encodes changes in ionisation state, kinematics, and accretion that ar…
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Time-domain astronomy is entering an era of unprecedented discovery driven by wide-field, high-cadence surveys such as LSST, Roman, Euclid, SKA, and PLATO. While some of these facilities will generate enormous photometric alert streams, the physical interpretation of variability and transients often requires spectroscopy, which encodes changes in ionisation state, kinematics, and accretion that are inaccessible to photometry alone. A critical gap is therefore emerging: next-generation surveys may produce up to $\sim10^9$ alerts per year, whereas global spectroscopic follow-up is limited to only $\sim10^4$--$10^5$ transient spectra annually. We present the concept of spectroscopic alerts: real-time notifications triggered by significant spectral evolution, enabling spectroscopy to act as a discovery channel rather than solely as follow-up. We outline the key science cases enabled by this capability and describe the instrumental and operational requirements of a wide-field, highly multiplexed spectroscopic facility capable of delivering real-time spectral discovery for 2040s time-domain and multi-messenger astronomy.
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Submitted 17 December, 2025;
originally announced December 2025.
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Transients as Determinants of Habitability
Authors:
Fatemeh Zahra Majidi,
Katia Biazzo,
Maria Tsantaki,
Amelia Bayo,
Gražina Tautvaišienė,
Valentin D. Ivanov,
Germano Sacco,
Richard I. Anderson,
Avraham Binnenfeld,
David Montes
Abstract:
Stellar magnetic activity, manifested through spots (faculae and flares), fundamentally shapes the exoplanets' environments. For low-mass stars in particular, where most habitable-zone planets reside, the variable magnetic phenomena can dominate atmospheric chemistry, surface radiation levels, long-term atmospheric escape, and ultimately habitability. However, physical characteristics of these tra…
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Stellar magnetic activity, manifested through spots (faculae and flares), fundamentally shapes the exoplanets' environments. For low-mass stars in particular, where most habitable-zone planets reside, the variable magnetic phenomena can dominate atmospheric chemistry, surface radiation levels, long-term atmospheric escape, and ultimately habitability. However, physical characteristics of these transients (e.g. energy and temperature) and their spectra remain ill-constrained due to limitations in cadence and magnitude access of current spectroscopic facilities. A next-generation 12-m class ground-based observatory equipped with integral-field spectroscopy (IFS) and multi-object spectroscopy (MOS) at R$\sim$4,000 and $\sim$40,000 offers a transformational opportunity to characterize stellar activity in the time domain across large samples of exoplanet host stars. Such a facility would enable simultaneous monitoring of continuum variability, chromospheric and coronal line diagnostics, and particle-accelerated flare signatures, resolving the physics driving space weather and quantifying its impact on planetary atmospheres.
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Submitted 13 December, 2025;
originally announced December 2025.
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Toward the time-domain spectroscopic study of the dynamic life of stars: from accretion to magnetic activity
Authors:
Fatemeh Zahra Majidi,
Amelia Bayo,
Marc Audard,
Francisco José Galindo-Guil,
Rosaria Bonito,
Katia Biazzo,
Loredana Prisinzano,
Mario Giuseppe Guarcello,
Eleonora Fiorellino,
Innocenza Busa,
Germano Sacco,
Richard I. Anderson,
Avraham Binnenfeld,
David Montes
Abstract:
Stars and planets can be seen as the second fundamental building blocks of baryons in the universe (only second to the dust and gas in molecular clouds). Their formation involves dust grain growth of many orders of magnitude and a myriad of processes operating at time scales from a few tens to millions of years. Thus, investigating the formation and evolution of young stellar objects (YSOs) is of…
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Stars and planets can be seen as the second fundamental building blocks of baryons in the universe (only second to the dust and gas in molecular clouds). Their formation involves dust grain growth of many orders of magnitude and a myriad of processes operating at time scales from a few tens to millions of years. Thus, investigating the formation and evolution of young stellar objects (YSOs) is of great importance in modern astronomy. Addressing this goal requires overcoming long-standing challenges in characterizing multifaceted phenomena that span a broad range of astrophysical processes (from protoplanetary disk evolution and planet formation to accretion dynamics and transient stellar events). Also, YSOs are complex systems that consist of several components: a central forming object, surrounded by a medium or disk from which the accretion process is at work, supersonic ejection of plasma in the form of collimated bipolar jets (which interact with the ambient medium through which they propagate) and all these components emit in a wide range of wavelengths. A facility capable of simultaneously tackling these diverse questions must deliver long-term, high-cadence spectroscopic monitoring of YSOs over time spans of at least a decade; especially because accretion/ejection processes in YSOs are characterized by a wide range of temporal variability: from short-term (hours-days) to long-term (months-years) variability due to rotation, accretion, magnetic activity, etc. Such a mission demands a spectroscopic platform considering a solid time-domain astronomy framework, providing repeated observations over wide fields and supporting multiple cadence strategies tailored to distinct scientific objectives.
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Submitted 13 December, 2025;
originally announced December 2025.
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A vision for ground-based astronomy beyond the 2030s: How to build ESO's next big telescope sustainably
Authors:
Laurane Fréour,
Mathilde Bouvier,
Tony Mroczkowski,
Callie Clontz,
Fatemeh Zahra Majidi,
Vasundhara Shaw,
Olivier Absil,
Anna Cabré,
Olivier Lai,
Dylan Magill,
Jake D. Turner
Abstract:
Astronomy is the study of the Universe and all the objects that it comprises. Our attention is therefore usually focused beyond Earth, home to the only form of life known today. However, how can we continue to explore the secrets of the Universe, if we stand by and watch our only home burn? We know that there is no Planet B. It is therefore urgent that, as astronomers, we collectively work to prot…
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Astronomy is the study of the Universe and all the objects that it comprises. Our attention is therefore usually focused beyond Earth, home to the only form of life known today. However, how can we continue to explore the secrets of the Universe, if we stand by and watch our only home burn? We know that there is no Planet B. It is therefore urgent that, as astronomers, we collectively work to protect the Earth, allowing future generations the opportunity to continue to uncover the secrets of the cosmos. As astronomical facilities account for the majority of our community's carbon footprint, we propose guidelines that we hold crucial for the European Southern Observatory (ESO) to consider in the context of the Expanding Horizons programme as it plans a next-generation, transformational facility.
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Submitted 11 December, 2025;
originally announced December 2025.
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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…
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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.
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Submitted 11 September, 2024;
originally announced September 2024.
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The Wide-field Spectroscopic Telescope (WST) Science White Paper
Authors:
Vincenzo Mainieri,
Richard I. Anderson,
Jarle Brinchmann,
Andrea Cimatti,
Richard S. Ellis,
Vanessa Hill,
Jean-Paul Kneib,
Anna F. McLeod,
Cyrielle Opitom,
Martin M. Roth,
Paula Sanchez-Saez,
Rodolfo Smiljanic,
Eline Tolstoy,
Roland Bacon,
Sofia Randich,
Angela Adamo,
Francesca Annibali,
Patricia Arevalo,
Marc Audard,
Stefania Barsanti,
Giuseppina Battaglia,
Amelia M. Bayo Aran,
Francesco Belfiore,
Michele Bellazzini,
Emilio Bellini
, et al. (192 additional authors not shown)
Abstract:
The Wide-field Spectroscopic Telescope (WST) is proposed as a new facility dedicated to the efficient delivery of spectroscopic surveys. This white paper summarises the initial concept as well as the corresponding science cases. WST will feature simultaneous operation of a large field-of-view (3 sq. degree), a high multiplex (20,000) multi-object spectrograph (MOS) and a giant 3x3 sq. arcmin integ…
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The Wide-field Spectroscopic Telescope (WST) is proposed as a new facility dedicated to the efficient delivery of spectroscopic surveys. This white paper summarises the initial concept as well as the corresponding science cases. WST will feature simultaneous operation of a large field-of-view (3 sq. degree), a high multiplex (20,000) multi-object spectrograph (MOS) and a giant 3x3 sq. arcmin integral field spectrograph (IFS). In scientific capability these requirements place WST far ahead of existing and planned facilities. Given the current investment in deep imaging surveys and noting the diagnostic power of spectroscopy, WST will fill a crucial gap in astronomical capability and work synergistically with future ground and space-based facilities. This white paper shows that WST can address outstanding scientific questions in the areas of cosmology; galaxy assembly, evolution, and enrichment, including our own Milky Way; origin of stars and planets; time domain and multi-messenger astrophysics. WST's uniquely rich dataset will deliver unforeseen discoveries in many of these areas. The WST Science Team (already including more than 500 scientists worldwide) is open to the all astronomical community. To register in the WST Science Team please visit https://www.wstelescope.com/for-scientists/participate
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Submitted 12 April, 2024; v1 submitted 8 March, 2024;
originally announced March 2024.
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A new dynamical modeling of the WASP-47 system with CHEOPS observations
Authors:
V. Nascimbeni,
L. Borsato,
T. Zingales,
G. Piotto,
I. Pagano,
M. Beck,
C. Broeg,
D. Ehrenreich,
S. Hoyer,
F. Z. Majidi,
V. Granata,
S. G. Sousa,
T. G. Wilson,
V. Van Grootel,
A. Bonfanti,
S. Salmon,
A. J. Mustill,
L. Delrez,
Y. Alibert,
R. Alonso,
G. Anglada,
T. Bárczy,
D. Barrado,
S. C. C. Barros,
W. Baumjohann
, et al. (58 additional authors not shown)
Abstract:
Among the hundreds of known hot Jupiters (HJs), only five have been found to have companions on short-period orbits. Within this rare class of multiple planetary systems, the architecture of WASP-47 is unique, hosting an HJ (planet -b) with both an inner and an outer sub-Neptunian mass companion (-e and -d, respectively) as well as an additional non-transiting, long-period giant (-c). The small pe…
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Among the hundreds of known hot Jupiters (HJs), only five have been found to have companions on short-period orbits. Within this rare class of multiple planetary systems, the architecture of WASP-47 is unique, hosting an HJ (planet -b) with both an inner and an outer sub-Neptunian mass companion (-e and -d, respectively) as well as an additional non-transiting, long-period giant (-c). The small period ratio between planets -b and -d boosts the transit time variation (TTV) signal, making it possible to reliably measure the masses of these planets in synergy with the radial velocity (RV) technique. In this paper, we present new space- and ground-based photometric data of WASP-47b and WASP-47-d, including 11 unpublished light curves from the ESA mission CHEOPS. We analyzed the light curves in a homogeneous way together with all the publicly available data to carry out a global $N$-body dynamical modeling of the TTV and RV signals. We retrieved, among other parameters, a mass and density for planet -d of $M_\mathrm{d}=15.5\pm 0.8$ $M_\oplus$ and $ρ_\mathrm{d}=1.69\pm 0.22$ g\,cm$^{-3}$, which is in good agreement with the literature and consistent with a Neptune-like composition. For the inner planet (-e), we found a mass and density of $M_\mathrm{e}=9.0\pm 0.5$ $M_\oplus$ and $ρ_\mathrm{e}=8.1\pm 0.5$ g\,cm$^{-3}$, suggesting an Earth-like composition close to other ultra-hot planets at similar irradiation levels. Though this result is in agreement with previous RV+TTV studies, it is not in agreement with the most recent RV analysis (at 2.8$σ$), which yielded a lower density compatible with a pure silicate composition. This discrepancy highlights the still unresolved issue of suspected systematic offsets between RV and TTV measurements. In this paper, we also significantly improve the orbital ephemerides of all transiting planets, which will be crucial for any future follow-up.
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Submitted 2 March, 2023; v1 submitted 2 February, 2023;
originally announced February 2023.
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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…
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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.
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Submitted 11 January, 2023;
originally announced January 2023.
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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…
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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.
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Submitted 25 August, 2022;
originally announced August 2022.
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Characterization of very wide companion candidates to young stars with planets and disks
Authors:
F. Z. Majidi,
S. Desidera,
J. M. Alcalá,
A. Frasca,
V. D'Orazi,
M. Bonnefoy,
R. Claudi,
R. Gratton,
D. Mesa
Abstract:
Discovering wide companions of stellar systems allows us to constrain the dynamical environment and age of the latter. We studied four probable wide companions of four different stellar systems. The central stars are V4046 Sgr, HIP 74865, HIP 65426, and HIP 73145, and their probable wide companions are 2MASS J18152222-3249329, 2MASS J15174874-3028484, 2MASS J13242119-5129503, and 2MASS J14571503-3…
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Discovering wide companions of stellar systems allows us to constrain the dynamical environment and age of the latter. We studied four probable wide companions of four different stellar systems. The central stars are V4046 Sgr, HIP 74865, HIP 65426, and HIP 73145, and their probable wide companions are 2MASS J18152222-3249329, 2MASS J15174874-3028484, 2MASS J13242119-5129503, and 2MASS J14571503-3543505 respectively. V4046 Sgr is a member of $β$-Pictoris Moving Group while the rest of the stellar systems are acknowledged as members of the Scorpius-Centaurus association. The selected stellar systems are particularly interesting because all of them are already known to possess a low-mass companion and/or a spatially resolved disk. Identifying wider companions of these stars can improve their eligibility as benchmarks for understanding the formation channels of various triple systems, and can help us to determine the orbits of their possibly undiscovered inner, wider companions in case of higher multiplicity. We find that 2MASS J15174874-3028484 (0.11 $M_{\odot}$, 7.4$\pm$0.5 Myr), an already recognized pre-main sequence (PMS) member of Scorpius-Centaurus association, is a highly probable wide companion of HIP 74865. 2MASS J13242119-5129503 (0.04 $M_{\odot}$, 16$\pm$2.2 Myr) is ruled out as a plausible wide companion of HIP 65426, but confirmed to be a new sub-stellar member of the Scorpius-Centaurus association. 2MASS J14571503-3543505 (0.02 $M_{\odot}$, 17.75$\pm$4.15 Myr) is a probable sub-stellar member of the same association, but we cannot confirm whether or not it is gravitationally bound to HIP 73145. 2MASS J18152222-3249329 (0.3 $M_{\odot}$, older than 150 Myr) is determined to be a mildly active main sequence (MS) star, much older than members of $β$-Pictoris Moving Group, and unbound to V4046 Sgr despite their similar kinematic features.
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Submitted 8 November, 2020;
originally announced November 2020.
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2MASS J15491331-3539118: a new low-mass wide companion of the GQ Lup system
Authors:
J. M. Alcalá,
F. Z. Majidi,
S. Desidera,
A. Frasca,
C. F. Manara,
E. Rigliaco,
R. Gratton,
M. Bonnefoy,
E. Covino,
G. Chauvin,
R. Claudi,
V. D'Orazi,
M. Langlois,
C. Lazzoni,
D. Mesa,
J. E. Schlieder,
A. Vigan
Abstract:
Substellar companions at wide separation around stars hosting planets or brown dwarfs (BDs) yet close enough for their formation in the circumstellar disc are of special interest. In this letter we report the discovery of a wide (projected separation $\sim$16.0arcsec, or 2400 AU, and position angle 114.61$^\circ$) companion of the GQ Lup A-B system, most likely gravitationally bound to it. A VLT/X…
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Substellar companions at wide separation around stars hosting planets or brown dwarfs (BDs) yet close enough for their formation in the circumstellar disc are of special interest. In this letter we report the discovery of a wide (projected separation $\sim$16.0arcsec, or 2400 AU, and position angle 114.61$^\circ$) companion of the GQ Lup A-B system, most likely gravitationally bound to it. A VLT/X-Shooter spectrum shows that this star, 2MASS J15491331-3539118, is a bonafide low-mass ($\sim$0.15 M$_\odot$) young stellar object (YSO) with stellar and accretion/ejection properties typical of Lupus YSOs of similar mass, and with kinematics consistent with that of the GQ Lup A-B system. A possible scenario for the formation of the triple system is that GQ Lup A and 2MASS J15491331-3539118 formed by fragmentation of a turbulent core in the Lup I filament, while GQ Lup B, the BD companion of GQ Lup A at 0.7arcsec, formed in situ by the fragmentation of the circumprimary disc. The recent discoveries that stars form along cloud filaments would favour the scenario of turbulent fragmentation for the formation of GQ Lup A and 2MASS J15491331-3539118.
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Submitted 3 February, 2020; v1 submitted 29 January, 2020;
originally announced January 2020.
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Another Kerr interior solution
Authors:
F. Z. Majidi
Abstract:
A stationary axially symmetric solution describing a rotating anisotropic source for Einstein Field Equations(EFE) is proposed which matches to the exterior Kerr metric. The anisotropic source satisfies all energy conditions - weak, strong, and dominant energy condition - for a wide range of metric's free parameters values. The resultant energy-momentum tensor components, and consequently energy d…
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A stationary axially symmetric solution describing a rotating anisotropic source for Einstein Field Equations(EFE) is proposed which matches to the exterior Kerr metric. The anisotropic source satisfies all energy conditions - weak, strong, and dominant energy condition - for a wide range of metric's free parameters values. The resultant energy-momentum tensor components, and consequently energy density and pressure profiles, redshift function and angular velocity are singularity free and behave as expected. As rotation parameter goes to zero a spherical source consisting of normal and exotic matter is retrieved for the exterior Schwarzschild solution; the corresponding redshift function, however, is well-behaved and positive definite. This is the first solution of its kind.
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Submitted 2 July, 2017; v1 submitted 1 May, 2017;
originally announced May 2017.