Showing 1–50 of 60 results for author: McCullough, P

Ground-based Atmospheric Characterization of Super-Earth L 98-59 d at High Spectral Resolution

Authors: Connor J. Cheverall, Nikku Madhusudhan, Savvas Constantinou, Peter R. McCullough

Abstract: Atmospheric characterization of exoplanets using ground-based high-resolution transmission spectroscopy has traditionally focussed on large and close-in planets, such as hot Jupiters. In this work, we aim to extend this technique to smaller and more temperate planets by studying the atmospheric composition of the temperate super-Earth planet L 98-59 d ($\sim$$1.5\,\mathrm{R_{\oplus}}$; $\sim$… ▽ More Atmospheric characterization of exoplanets using ground-based high-resolution transmission spectroscopy has traditionally focussed on large and close-in planets, such as hot Jupiters. In this work, we aim to extend this technique to smaller and more temperate planets by studying the atmospheric composition of the temperate super-Earth planet L 98-59 d ($\sim$$1.5\,\mathrm{R_{\oplus}}$; $\sim$$1.9\,\mathrm{M_{\oplus}}$). Using high-resolution transmission spectra obtained using IGRINS on the Gemini-South telescope, we demonstrate the feasibility for atmospheric characterization of super-Earths using ground-based facilities, and confirm the previous tentative JWST inference of hydrogen sulfide (H2S) in the atmosphere of L 98-59 d at $\lesssim$3.9$\,σ$ ($B\sim390$). This is the first ground-based inference of a molecular species in the atmosphere of a super-Earth planet, and reveals the sensitivity of spectrographs on 8m-class telescopes to the atmospheric characterization of such planets. By exploring a grid of atmospheric models, we find that the data favors a cloud-free atmosphere with an abundance of H2S corresponding to $\sim$1-10$\times$ solar metallicity. We additionally place constraints on the atmospheric abundances of other molecular species. Assuming cloud-free models, super-solar abundances for CH4 and NH3 are ruled out at 3.6$σ$ and $4.6σ$, respectively. Our results are consistent with previous suggestions that L 98-59 d is a super-Earth with possible disequilibrium production of H2S driven by volcanic outgassing from the surface. Future studies combining multiple observations with different facilities may be able to further constrain the atmospheric composition of this planet. This work underscores the promise of atmospheric characterization of super-Earth exoplanets using high-resolution spectroscopy with ground-based facilities. △ Less

Submitted 10 March, 2026; v1 submitted 2 March, 2026; originally announced March 2026.

Comments: Accepted for publication in MNRAS 01 March 2026

Journal ref: Mon Not R Astron Soc (2026)

WFC3/IR Starter Guide

Authors: P. R. McCullough, Joel D. Green

Abstract: In this starter guide, we provide a high-level overview of analysis of WFC3/IR data available from the Mikulski Archive for Space Telescopes (MAST). We intend this guide as a starting point for users examining WFC3/IR data for the first time, or for those refreshing their memory on WFC3/IR data analysis. Therefore, we focus on the analysis of archival data, not preparing new observations. Three ap… ▽ More In this starter guide, we provide a high-level overview of analysis of WFC3/IR data available from the Mikulski Archive for Space Telescopes (MAST). We intend this guide as a starting point for users examining WFC3/IR data for the first time, or for those refreshing their memory on WFC3/IR data analysis. Therefore, we focus on the analysis of archival data, not preparing new observations. Three appendices include A) a summary of the instrument and an optical schematic, B) examples from the Exposure Time Calculator, and C) a glossary of uncommon acronyms. This report addresses only data from WFC3's IR channel; not the UVIS channel. △ Less

Submitted 11 November, 2025; originally announced November 2025.

Comments: 20 pages, 8 figures, 3 tables

Report number: WFC3 ISR-2025-03

A Study of Stellar Spins in 15 Open Clusters

Authors: Brian F. Healy, P. R. McCullough, Kevin C. Schlaufman, Geza Kovacs

Abstract: We analyze spectroscopic and photometric data to determine the projected inclinations of stars in 11 open clusters, placing constraints on the spin-axis distributions of six clusters. We combine these results with four additional clusters studied by Healy & McCullough (2020) and Healy et al. (2021) to perform an ensemble analysis of their spins. We find that eight out of ten constrained clusters (… ▽ More We analyze spectroscopic and photometric data to determine the projected inclinations of stars in 11 open clusters, placing constraints on the spin-axis distributions of six clusters. We combine these results with four additional clusters studied by Healy & McCullough (2020) and Healy et al. (2021) to perform an ensemble analysis of their spins. We find that eight out of ten constrained clusters (80%) have spin-axis orientations consistent with isotropy, and we establish a lower limit of four out of ten (40%) isotropic clusters at 75% confidence, assuming no correlation of spins between clusters. We also identify two clusters whose spin-axis distributions can be better described by a model consisting of an aligned fraction of stars combined with an isotropic distribution. However, the inclination values of these stars may be influenced by systematic error, and the small number of stars modeled as aligned in these two clusters precludes the interpretation that their stellar subsets are physically aligned. Overall, no cluster displays an unambiguous signature of spin alignment, and 97% of the stars in our sample are consistent with isotropic orientations in their respective clusters. Our results offer support for the dominance of turbulence over ordered rotation in clumps and do not suggest alignment of rotation axes and magnetic fields in protostars. △ Less

Submitted 24 January, 2023; originally announced January 2023.

Comments: 35 pages, 15 figures, accepted for publication in ApJ

Evidence for the volatile-rich composition of a 1.5-$R_\oplus$ planet

Authors: Caroline Piaulet, Björn Benneke, Jose M. Almenara, Diana Dragomir, Heather A. Knutson, Daniel Thorngren, Merrin S. Peterson, Ian J. M. Crossfield, Eliza M. -R. Kempton, Daria Kubyshkina, Andrew W. Howard, Ruth Angus, Howard Isaacson, Lauren M. Weiss, Charles A. Beichman, Jonathan J. Fortney, Luca Fossati, Helmut Lammer, P. R. McCullough, Caroline V. Morley, Ian Wong

Abstract: The population of planets smaller than approximately $1.7~R_\oplus$ is widely interpreted as consisting of rocky worlds, generally referred to as super-Earths. This picture is largely corroborated by radial-velocity (RV) mass measurements for close-in super-Earths but lacks constraints at lower insolations. Here we present the results of a detailed study of the Kepler-138 system using 13 Hubble an… ▽ More The population of planets smaller than approximately $1.7~R_\oplus$ is widely interpreted as consisting of rocky worlds, generally referred to as super-Earths. This picture is largely corroborated by radial-velocity (RV) mass measurements for close-in super-Earths but lacks constraints at lower insolations. Here we present the results of a detailed study of the Kepler-138 system using 13 Hubble and Spitzer transit observations of the warm-temperate $1.51\pm0.04~R_\oplus$ planet Kepler-138 d ($T_{\mathrm{eq, A_B=0.3}}$~350 K) combined with new Keck/HIRES RV measurements of its host star. We find evidence for a volatile-rich "water world" nature of Kepler-138 d, with a large fraction of its mass contained in a thick volatile layer. This finding is independently supported by transit timing variations, RV observations ($M_d=2.1_{-0.7}^{+0.6}~M_\oplus$), as well as the flat optical/IR transmission spectrum. Quantitatively, we infer a composition of $11_{-4}^{+3}$\% volatiles by mass or ~51% by volume, with a 2000 km deep water mantle and atmosphere on top of a core with an Earth-like silicates/iron ratio. Any hypothetical hydrogen layer consistent with the observations ($<0.003~M_\oplus$) would have swiftly been lost on a ~10 Myr timescale. The bulk composition of Kepler-138 d therefore resembles those of the icy moons rather than the terrestrial planets in the solar system. We conclude that not all super-Earth-sized planets are rocky worlds, but that volatile-rich water worlds exist in an overlapping size regime, especially at lower insolations. Finally, our photodynamical analysis also reveals that Kepler-138 c ($R_c=1.51 \pm 0.04~R_\oplus$, $M_c=2.3_{-0.5}^{+0.6}~M_\oplus$) is a slightly warmer twin of Kepler-138 d, i.e., another water world in the same system, and we infer the presence of Kepler-138 e, a likely non-transiting planet at the inner edge of the habitable zone. △ Less

Submitted 14 December, 2022; originally announced December 2022.

Comments: Published in Nature Astronomy. 4 main figures, 10 extended data figures, 13 supplementary figures. 4 tables

Stellar Spins in the Pleiades, Praesepe, and M35 Open Clusters

Authors: Brian F. Healy, P. R. McCullough, Kevin C. Schlaufman

Abstract: We analyze spectroscopic and photometric data to determine the projected inclinations of stars in three open clusters: the Pleiades, Praesepe, and M35. We determine the $\sin i$ values of 42, 35, and 67 stars in each cluster, respectively, and from their distributions we find that isotropic spins and moderate alignment are both consistent with the Pleiades and Praesepe data. While it is difficult… ▽ More We analyze spectroscopic and photometric data to determine the projected inclinations of stars in three open clusters: the Pleiades, Praesepe, and M35. We determine the $\sin i$ values of 42, 35, and 67 stars in each cluster, respectively, and from their distributions we find that isotropic spins and moderate alignment are both consistent with the Pleiades and Praesepe data. While it is difficult to distinguish between these scenarios for a single cluster, an ensemble of such distributions may facilitate a distinction. The M35 inclination distribution is most consistent with a superposition of isotropic and anisotropic spins, the source of which could be systematic error or a physical grouping of aligned stars. We also study internal cluster kinematics using radial velocities and proper motions. Our kinematics analysis reveals significant plane-of-sky rotation in Praesepe, with a mean velocity of $0.132 \pm 0.022$ km s$^{-1}$ in a clockwise direction. △ Less

Submitted 5 November, 2021; v1 submitted 17 September, 2021; originally announced September 2021.

Comments: 24 pages, 11 figures, accepted for publication in ApJ

Stellar Spins in the Open Cluster NGC 2516

Authors: Brian F. Healy, P. R. McCullough

Abstract: Measuring the distribution of stellar spin axis orientations in a coeval group of stars probes the physical processes underlying the stars' formation. In this paper, we use spectro-photometric observations of the open cluster NGC 2516 to determine the degree of spin alignment among its stars. We combine TESS light curves, ground-based spectroscopy from the Gaia-ESO and GALAH surveys, broad-band st… ▽ More Measuring the distribution of stellar spin axis orientations in a coeval group of stars probes the physical processes underlying the stars' formation. In this paper, we use spectro-photometric observations of the open cluster NGC 2516 to determine the degree of spin alignment among its stars. We combine TESS light curves, ground-based spectroscopy from the Gaia-ESO and GALAH surveys, broad-band stellar magnitudes from several surveys, and Gaia astrometry to measure 33 stellar inclinations and quantify overall cluster rotation. Our measurements suggest that stellar spins in this cluster are isotropically oriented, while allowing for the possibility that they are moderately aligned. An isotropic distribution of NGC 2516 spins would imply a star-forming environment in which turbulence dominated ordered motion, while a moderately aligned distribution would suggest a more substantial contribution from rotation. We also perform a three-dimensional analysis of the cluster's internal kinematics, finding no significant signatures of overall rotation. Stemming from this analysis, we identify evidence of cluster contraction, suggesting possible ongoing mass segregation in NGC 2516. △ Less

Submitted 6 November, 2020; v1 submitted 29 September, 2020; originally announced September 2020.

Comments: 22 pages, 15 figures, accepted for publication in ApJ

Journal ref: ApJ 903 (2020), 99

Updated Parameters and a New Transmission Spectrum of HD 97658b

Authors: Xueying Guo, Ian J. M. Crossfield, Diana Dragomir, Molly R. Kosiarek, Joshua Lothringer, Thomas Mikal-Evans, Lee Rosenthal, Bjorn Benneke, Heather A. Knutson, Paul A. Dalba, Eliza M. R. Kempton, Gregory W. Henry, P. R. McCullough, Travis Barman, Sarah Blunt, Ashley Chontos, Jonathan Fortney, Benjamin J. Fulton, Lea Hirsch, Andrew W. Howard, Howard Isaacson, Jaymie Matthews, Teo Mocnik, Caroline Morley, Erik A. Petigura , et al. (1 additional authors not shown)

Abstract: Recent years have seen increasing interest in the characterization of sub-Neptune sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD 97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four HST transits, twelve Spitzer/IRAC transits, and eight MOST transit… ▽ More Recent years have seen increasing interest in the characterization of sub-Neptune sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD 97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four HST transits, twelve Spitzer/IRAC transits, and eight MOST transits of this system. Our transmission spectrum has higher signal to noise ratio than that from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1 to 1.7 microns reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are not conclusive as no model provides an excellent match to our data. Nonetheless we find that atmospheres with high C/O ratios (C/O >~ 0.8) and metallicities of >~ 100x solar metallicity are favored. We combine the mid-transit times from all the new Spitzer and MOST observations and obtain an updated orbital period of P=9.489295 +/- 0.000005 d, with a best-fit transit time center at T_0 = 2456361.80690 +/- 0.00038 (BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34 +/- 2 d) and stellar activity cycle (9.6 yr) of the host star HD 97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000 K and with sizes between 1 and 4 R_Earth. We find that at least a third of small planets cooler than 1000 K can be well characterized using JWST, and of those, HD 97658b is ranked fifth, meaning it remains a high-priority target for atmospheric characterization. △ Less

Submitted 17 April, 2020; v1 submitted 7 April, 2020; originally announced April 2020.

Comments: Accepted to AJ. 29 pages, 21 figures, 11 tables, 2 machine-readable tables (system RVs and TSM values). v2: updated typos

XO-7 b: A transiting hot Jupiter with a massive companion on a wide orbit

Authors: Nicolas Crouzet, Brian F. Healy, Guillaume Hébrard, P. R. McCullough, Doug Long, Pilar Montañés-Rodríguez, Ignasi Ribas, Francesc Vilardell, Enrique Herrero, Enrique Garcia-Melendo, Matthieu Conjat, Jerry Foote, Joe Garlitz, Phillip Vo, Nuno C. Santos, Jos de Bruijne, Hugh P. Osborn, Shweta Dalal, Louise D. Nielsen

Abstract: Transiting planets orbiting bright stars are the most favorable targets for follow-up and characterization. We report the discovery of the transiting hot Jupiter XO-7 b and of a second, massive companion on a wide orbit around a circumpolar, bright, and metal rich G0 dwarf (V = 10.52, $T_{\rm eff} = 6250 \pm 100 \; \rm K$, $\rm[Fe/H] = 0.432 \pm 0.057 \; \rm dex$). We conducted photometric and rad… ▽ More Transiting planets orbiting bright stars are the most favorable targets for follow-up and characterization. We report the discovery of the transiting hot Jupiter XO-7 b and of a second, massive companion on a wide orbit around a circumpolar, bright, and metal rich G0 dwarf (V = 10.52, $T_{\rm eff} = 6250 \pm 100 \; \rm K$, $\rm[Fe/H] = 0.432 \pm 0.057 \; \rm dex$). We conducted photometric and radial velocity follow-up with a team of amateur and professional astronomers. XO-7 b has a period of $ 2.8641424 \pm 0.0000043$ days, a mass of $0.709 \pm 0.034 \; \rm M_{\rm J}$, a radius of $1.373 \pm 0.026 \; \rm R_{\rm J}$, a density of $0.340 \pm 0.027 \; \rm g \, {cm}^{-3}$, and an equilibrium temperature of $1743 \pm 23 \; \rm K$. Its large atmospheric scale height and the brightness of the host star make it well suited to atmospheric characterization. The wide orbit companion is detected as a linear trend in radial velocities with an amplitude of $\sim100 \; \rm m \, {s}^{-1}$ over two years, yielding a minimum mass of $4 \; \rm M_{\rm J}$; it could be a planet, a brown dwarf, or a low mass star. The hot Jupiter orbital parameters and the presence of the wide orbit companion point towards a high eccentricity migration for the hot Jupiter. Overall, this system will be valuable to understand the atmospheric properties and migration mechanisms of hot Jupiters and will help constrain the formation and evolution models of gas giant exoplanets. △ Less

Submitted 5 December, 2019; originally announced December 2019.

Comments: 16 pages, 6 figures, Accepted for publication in AJ

Water Vapor and Clouds on the Habitable-Zone Sub-Neptune Exoplanet K2-18b

Authors: Björn Benneke, Ian Wong, Caroline Piaulet, Heather A. Knutson, Joshua Lothringer, Caroline V. Morley, Ian J. M. Crossfield, Peter Gao, Thomas P. Greene, Courtney Dressing, Diana Dragomir, Andrew W. Howard, Peter R. McCullough, Eliza M. -R. Kempton, Jonathan J. Fortney, Jonathan Fraine

Abstract: Results from the Kepler mission indicate that the occurrence rate of small planets ($<3$ $R_\oplus$) in the habitable zone of nearby low-mass stars may be as high as 80%. Despite this abundance, probing the conditions and atmospheric properties on any habitable-zone planet is extremely difficult and has remained elusive to date. Here, we report the detection of water vapor and the likely presence… ▽ More Results from the Kepler mission indicate that the occurrence rate of small planets ($<3$ $R_\oplus$) in the habitable zone of nearby low-mass stars may be as high as 80%. Despite this abundance, probing the conditions and atmospheric properties on any habitable-zone planet is extremely difficult and has remained elusive to date. Here, we report the detection of water vapor and the likely presence of liquid and icy water clouds in the atmosphere of the $2.6$ $R_\oplus$ habitable-zone planet K2-18b. The simultaneous detection of water vapor and clouds in the mid-atmosphere of K2-18b is particularly intriguing because K2-18b receives virtually the same amount of total insolation from its host star ($1368_{-107}^{+114}$ W m$^{-2}$) as the Earth receives from the Sun (1361 W m$^{-2}$), resulting in the right conditions for water vapor to condense and explain the detected clouds. In this study, we observed nine transits of K2-18b using HST/WFC3 in order to achieve the necessary sensitivity to detect the water vapor, and we supplement this data set with Spitzer and K2 observations to obtain a broader wavelength coverage. While the thick hydrogen-dominated envelope we detect on K2-18b means that the planet is not a true Earth analog, our observations demonstrate that low-mass habitable-zone planets with the right conditions for liquid water are accessible with state-of-the-art telescopes. △ Less

Submitted 12 December, 2019; v1 submitted 10 September, 2019; originally announced September 2019.

Comments: Published in ApJL, includes important updates to stellar and planet parameters

Journal ref: ApJL, 887, L14 (2019)

A Sub-Neptune Exoplanet with a Low-Metallicity Methane-Depleted Atmosphere and Mie-Scattering Clouds

Authors: Björn Benneke, Heather A. Knutson, Joshua Lothringer, Ian J. M. Crossfield, Julianne I. Moses, Caroline Morley, Laura Kreidberg, Benjamin J. Fulton, Diana Dragomir, Andrew W. Howard, Ian Wong, Jean-Michel Désert, Peter R. McCullough, Eliza M. -R. Kempton, Jonathan Fortney, Ronald Gilliland, Drake Deming, Joshua Kammer

Abstract: With no analogues in the Solar System, the discovery of thousands of exoplanets with masses and radii intermediate between Earth and Neptune was one of the big surprises of exoplanet science. These super-Earths and sub-Neptunes likely represent the most common outcome of planet formation. Mass and radius measurements indicate a diversity in bulk composition much wider than for gas giants; however,… ▽ More With no analogues in the Solar System, the discovery of thousands of exoplanets with masses and radii intermediate between Earth and Neptune was one of the big surprises of exoplanet science. These super-Earths and sub-Neptunes likely represent the most common outcome of planet formation. Mass and radius measurements indicate a diversity in bulk composition much wider than for gas giants; however, direct spectroscopic detections of molecular absorption and constraints on the gas mixing ratios have largely remained limited to planets more massive than Neptune. Here, we analyze a combined Hubble/Spitzer Space Telescope dataset of 12 transits and 20 eclipses of the sub-Neptune GJ 3470 b, whose mass of 12.6 $M_\oplus$ places it near the half-way point between previously studied exo-Neptunes (22-23 $M_\oplus$) and exoplanets known to have rocky densities (7 $M_\oplus$). Obtained over many years, our data set provides a robust detection of water absorption (>5$σ$) and a thermal emission detection from the lowest irradiated planet to date. We reveal a low-metallicity, hydrogen-dominated atmosphere similar to a gas giant, but strongly depleted in methane gas. The low, near-solar metallicity (O/H=0.2-18) sets important constraints on the potential planet formation processes at low masses as well as the subsequent accretion of solids. The low methane abundance indicates that methane is destroyed much more efficiently than previously predicted, suggesting that the CH$_4$/CO transition curve has to be revisited for close-in planets. Finally, we also find a sharp drop in the cloud opacity at 2-3 $μ$m characteristic of Mie scattering, which enables narrow constraints on the cloud particle size and makes GJ 3470b a keystone target for mid-IR characterization with JWST. △ Less

Submitted 30 June, 2019; originally announced July 2019.

Comments: Published in Nature Astronomy (July 1, 2019)

Statistical Characterization of Hot Jupiter Atmospheres using Spitzer's Secondary Eclipses

Authors: Emily Garhart, Drake Deming, Avi Mandell, Heather A. Knutson, Nicole Wallack, Adam Burrows, Jonathan J. Fortney, Callie Hood, Christopher Seay, David K. Sing, Bjorn Benneke, Jonathan D. Fraine, Tiffany Kataria, Nikole Lewis, Nikku Madhusudhan, Peter McCullough, Kevin B. Stevenson, Hannah Wakeford

Abstract: We report 78 secondary eclipse depths for a sample of 36 transiting hot Jupiters observed at 3.6- and 4.5 microns using the Spitzer Space Telescope. Our eclipse results for 27 of these planets are new, and include highly irradiated worlds such as KELT-7b, WASP-87b, WASP-76b, and WASP-64b, and important targets for JWST such as WASP-62b. We find that WASP-62b has a slightly eccentric orbit e cos(om… ▽ More We report 78 secondary eclipse depths for a sample of 36 transiting hot Jupiters observed at 3.6- and 4.5 microns using the Spitzer Space Telescope. Our eclipse results for 27 of these planets are new, and include highly irradiated worlds such as KELT-7b, WASP-87b, WASP-76b, and WASP-64b, and important targets for JWST such as WASP-62b. We find that WASP-62b has a slightly eccentric orbit e cos(omega) = 0.00614+/- 0.00064, and we confirm the eccentricity of HAT-P-13b and WASP-14b. The remainder are individually consistent with circular orbits, but we find statistical evidence for eccentricity increasing with orbital period in our range from 1 to 5 days. Our day-side brightness temperatures for the planets yield information on albedo and heat redistribution, following Cowan and Agol (2011). Planets having maximum day side temperatures exceeding ~ 2200K are consistent with zero albedo and distribution of stellar irradiance uniformly over the day-side hemisphere. Our most intriguing result is that we detect a systematic difference between the emergent spectra of these hot Jupiters as compared to blackbodies. The ratio of observed brightness temperatures, Tb(4.5)/Tb(3.6), increases with equilibrium temperature by 100 +/- 24 parts-per-million per Kelvin, over the entire temperature range in our sample (800K to 2500K). No existing model predicts this trend over such a large range of temperature. We suggest that this may be due to a structural difference in the atmospheric temperature profile between the real planetary atmospheres as compared to models. △ Less

Submitted 23 January, 2020; v1 submitted 21 January, 2019; originally announced January 2019.

Comments: accepted for publication in AJ

TESS Discovery of a Transiting Super-Earth in the $π$ Mensae System

Authors: Chelsea X. Huang, Jennifer Burt, Andrew Vanderburg, Maximilian N. Günther, Avi Shporer, Jason A. Dittmann, Joshua N. Winn, Rob Wittenmyer, Lizhou Sha, Stephen R. Kane, George R. Ricker, Roland K. Vanderspek, David W. Latham, Sara Seager, Jon M. Jenkins, Douglas A. Caldwell, Karen A. Collins, Natalia Guerrero, Jeffrey C. Smith, Samuel N. Quinn, Stéphane Udry, Francesco Pepe, François Bouchy, Damien Ségransan, Christophe Lovis , et al. (23 additional authors not shown)

Abstract: We report the detection of a transiting planet around $π$ Mensae (HD 39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The solar-type host star is unusually bright (V=5.7) and was already known to host a Jovian planet on a highly eccentric, 5.7-year orbit. The newly discovered planet has a size of $2.04\pm 0.05$ $R_\oplus$ and an orbital period of 6.27 days. Radial-velocity… ▽ More We report the detection of a transiting planet around $π$ Mensae (HD 39091), using data from the Transiting Exoplanet Survey Satellite (TESS). The solar-type host star is unusually bright (V=5.7) and was already known to host a Jovian planet on a highly eccentric, 5.7-year orbit. The newly discovered planet has a size of $2.04\pm 0.05$ $R_\oplus$ and an orbital period of 6.27 days. Radial-velocity data from the HARPS and AAT/UCLES archives also displays a 6.27-day periodicity, confirming the existence of the planet and leading to a mass determination of $4.82\pm 0.85$ $M_\oplus$. The star's proximity and brightness will facilitate further investigations, such as atmospheric spectroscopy, asteroseismology, the Rossiter--McLaughlin effect, astrometry, and direct imaging. △ Less

Submitted 8 November, 2018; v1 submitted 16 September, 2018; originally announced September 2018.

Comments: Accepted for publication ApJ Letters. This letter makes use of the TESS Alert data, which is currently in a beta test phase. The discovery light curve is included in a table inside the arxiv submission

An HST/STIS Optical Transmission Spectrum of Warm Neptune GJ 436b

Authors: Joshua D. Lothringer, Björn Benneke, Ian J. M. Crossfield, Gregory W. Henry, Caroline Morley, Diana Dragomir, Travis Barman, Heather Knutson, Eliza Kempton, Jonathan Fortney, Peter McCullough, Andrew W. Howard

Abstract: GJ 436b is a prime target for understanding warm Neptune exoplanet atmospheres and a target for multiple JWST GTO programs. Here, we report the first space-based optical transmission spectrum of the planet using two HST/STIS transit observations from 0.53-1.03 microns. We find no evidence for alkali absorption features, nor evidence of a scattering slope longward of 0.53 microns. The spectrum is i… ▽ More GJ 436b is a prime target for understanding warm Neptune exoplanet atmospheres and a target for multiple JWST GTO programs. Here, we report the first space-based optical transmission spectrum of the planet using two HST/STIS transit observations from 0.53-1.03 microns. We find no evidence for alkali absorption features, nor evidence of a scattering slope longward of 0.53 microns. The spectrum is indicative of moderate to high metallicity (~100-1000x solar) while moderate metallicity scenarios (~100x solar) require aerosol opacity. The optical spectrum also rules out some highly scattering haze models. We find an increase in transit depth around 0.8 microns in the transmission spectra of 3 different sub-Jovian exoplanets (GJ 436b, HAT-P-26b, and GJ 1214b). While most of the data come from STIS, data from three other instruments may indicate this is not an instrumental effect. Only the transit spectrum of GJ 1214b is well fit by a model with stellar plages on the photosphere of the host star. Our photometric monitoring of the host star reveals a stellar rotation rate of 44.1 days and an activity cycle of 7.4 years. Intriguingly, GJ 436 does not become redder as it gets dimmer, which is expected if star spots were dominating the variability. These insights into the nature of the GJ 436 system help refine our expectations for future observations in the era of JWST, whose higher precision and broader wavelength coverage will shed light on the composition and structure of GJ 436b's atmosphere. △ Less

Submitted 1 January, 2018; originally announced January 2018.

Comments: 20 pages, 11 figures, 5 tables, Accepted to AJ. A full version of table 1 is included as table1_mrt.txt

Planet Detection Simulations for Several Possible TESS Extended Missions

Authors: L. G. Bouma, Joshua N. Winn, Jacobi Kosiarek, P. R. McCullough

Abstract: The Transiting Exoplanet Survey Satellite (TESS) will perform a two-year survey of nearly the entire sky, with the main goal of detecting exoplanets smaller than Neptune around bright and nearby stars. There do not appear to be any fundamental obstacles to continuing science operations for at least several years after the two-year Primary Mission. To provide a head start to those who will plan and… ▽ More The Transiting Exoplanet Survey Satellite (TESS) will perform a two-year survey of nearly the entire sky, with the main goal of detecting exoplanets smaller than Neptune around bright and nearby stars. There do not appear to be any fundamental obstacles to continuing science operations for at least several years after the two-year Primary Mission. To provide a head start to those who will plan and propose for such a mission, we present simulations of exoplanet detections in a third year of TESS operations. Our goal is to provide a helpful reference for the exoplanet-related aspects of any Extended Mission, while recognizing this will be only one part of a larger community discussion of the scientific goals. We use Monte Carlo simulations to try and anticipate the quantities and types of planets that would be detected in each of 6 plausible scenarios for a one-year Extended Mission following the two-year Primary Mission. We find that: (1) there is no sharp fall-off in the planet discovery rate in the third year; (2) the quantity of newly detected sub-Neptune radius planets does not depend strongly on the schedule of pointings; (3) an important function of an Extended Mission would be improving our ability to predict the times of future transits and occultations of TESS-detected planets. △ Less

Submitted 24 May, 2017; originally announced May 2017.

Comments: The views, opinions, assumptions, examples, and results expressed in this article are solely those of the authors and do not necessarily reflect the official policy or position of the TESS Science Team, any of the authors' employers or affiliated institutions, NASA, or any agency of the U.S. government. This article has not been endorsed or reviewed by NASA or the TESS Science Team

Discovery of XO-6b: a hot Jupiter transiting a fast rotating F5 star on an oblique orbit

Authors: N. Crouzet, P. R. McCullough, D. Long, P. Montanes Rodriguez, A. Lecavelier des Etangs, I. Ribas, V. Bourrier, G. Hébrard, F. Vilardell, M. Deleuil, E. Herrero, E. Garcia-Melendo, L. Akhenak, J. Foote, B. Gary, P. Benni, T. Guillot, M. Conjat, D. Mékarnia, J. Garlitz, C. J. Burke, B. Courcol, O. Demangeon

Abstract: Only a few hot Jupiters are known to orbit around fast rotating stars. These exoplanets are harder to detect and characterize and may be less common than around slow rotators. Here, we report the discovery of the transiting hot Jupiter XO-6b, which orbits a bright, hot, and fast rotating star: V = 10.25, Teff = 6720 +/- 100 K, v sin i = 48 +/- 3 km/s. We detected the planet from its transits using… ▽ More Only a few hot Jupiters are known to orbit around fast rotating stars. These exoplanets are harder to detect and characterize and may be less common than around slow rotators. Here, we report the discovery of the transiting hot Jupiter XO-6b, which orbits a bright, hot, and fast rotating star: V = 10.25, Teff = 6720 +/- 100 K, v sin i = 48 +/- 3 km/s. We detected the planet from its transits using the XO instruments and conducted a follow-up campaign. Because of the fast stellar rotation, radial velocities taken along the orbit do not yield the planet's mass with a high confidence level, but we secure a 3-sigma upper limit Mp < 4.4 MJup. We also obtain high resolution spectroscopic observations of the transit with the SOPHIE spectrograph at the 193-cm telescope of the Observatoire de Haute-Provence and analyze the stellar lines profile by Doppler tomography. The transit is clearly detected in the spectra. The radii measured independently from the tomographic analysis and from the photometric lightcurves are consistent, showing that the object detected by both methods is the same and indeed transits in front of XO-6. We find that XO-6b lies on a prograde and misaligned orbit with a sky-projected obliquity lambda = -20.7 +/- 2.3 deg. The rotation period of the star is shorter than the orbital period of the planet: Prot < 2.12 days, Porb = 3.77 days. Thus, this system stands in a largely unexplored regime of dynamical interactions between close-in giant planets and their host stars. △ Less

Submitted 12 January, 2017; v1 submitted 8 December, 2016; originally announced December 2016.

Comments: 12 pages, 11 figures, Accepted for publication in AJ

The Transiting Exoplanet Survey Satellite: Simulations of planet detections and astrophysical false positives

Authors: Peter W. Sullivan, Joshua N. Winn, Zachory K. Berta-Thompson, David Charbonneau, Drake Deming, Courtney D. Dressing, David W. Latham, Alan M. Levine, Peter R. McCullough, Timothy Morton, George R. Ricker, Roland Vanderspek, Deborah Woods

Abstract: The Transiting Exoplanet Survey Satellite (TESS) is a NASA-sponsored Explorer mission that will perform a wide-field survey for planets that transit bright host stars. Here, we predict the properties of the transiting planets that TESS will detect along with the eclipsing binary stars that produce false-positive photometric signals. The predictions are based on Monte Carlo simulations of the nearb… ▽ More The Transiting Exoplanet Survey Satellite (TESS) is a NASA-sponsored Explorer mission that will perform a wide-field survey for planets that transit bright host stars. Here, we predict the properties of the transiting planets that TESS will detect along with the eclipsing binary stars that produce false-positive photometric signals. The predictions are based on Monte Carlo simulations of the nearby population of stars, occurrence rates of planets derived from Kepler, and models for the photometric performance and sky coverage of the TESS cameras. We expect that TESS will find approximately 1700 transiting planets from 200,000 pre-selected target stars. This includes 556 planets smaller than twice the size of Earth, of which 419 are hosted by M dwarf stars and 137 are hosted by FGK dwarfs. Approximately 130 of the $R < 2~R_\oplus$ planets will have host stars brighter than K = 9. Approximately 48 of the planets with $R < 2~R_\oplus$ lie within or near the habitable zone ($0.2 < S/S_\oplus < 2$), and between 2-7 such planets have host stars brighter than K = 9. We also expect approximately 1100 detections of planets with radii 2-4 R_Earth, and 67 planets larger than $4~R_\oplus$. Additional planets larger than $2~R_\oplus$ can be detected around stars that are not among the pre-selected target stars, because TESS will also deliver full-frame images at a 30-minute cadence. The planet detections are accompanied by over one thousand astrophysical false positives. We discuss how TESS data and ground-based observations can be used to distinguish the false positives from genuine planets. We also discuss the prospects for follow-up observations to measure the masses and atmospheres of the TESS planets. △ Less

Submitted 8 March, 2017; v1 submitted 11 June, 2015; originally announced June 2015.

Comments: Corrected errors in Figs. 3 and 18 as documented in https://doi.org/10.3847/1538-4357/837/1/99

Journal ref: ApJ, 809, 77 (2015)

Observations of Transiting Exoplanets with the James Webb Space Telescope (JWST), Publications of the Astronomical Society of the Pacific (PASP), December 2014

Authors: Charles Beichman, Bjoern Benneke, Heather Knutson, Roger Smith, Courtney Dressing, David Latham, Drake Deming, Jonathan Lunine, Pierre-Olivier Lagage, Alessandro Sozzetti, Charles Beichman, David Sing, Eliza Kempton, George Ricker, Jacob Bean, Laura Kreidberg, Jeroen Bouwman, Ian Crossfield, Jessie Christiansen, David Ciardi, Jonathan Fortney, Loïc Albert, René Doyon, Marcia Rieke, George Rieke , et al. (23 additional authors not shown)

Abstract: This article summarizes a workshop held on March, 2014, on the potential of the James Webb Space Telescope (JWST) to revolutionize our knowledge of the physical properties of exoplanets through transit observations. JWST's unique combination of high sensitivity and broad wavelength coverage will enable the accurate measurement of transits with high signal-to-noise. Most importantly, JWST spectrosc… ▽ More This article summarizes a workshop held on March, 2014, on the potential of the James Webb Space Telescope (JWST) to revolutionize our knowledge of the physical properties of exoplanets through transit observations. JWST's unique combination of high sensitivity and broad wavelength coverage will enable the accurate measurement of transits with high signal-to-noise. Most importantly, JWST spectroscopy will investigate planetary atmospheres to determine atomic and molecular compositions, to probe vertical and horizontal structure, and to follow dynamical evolution, i.e. exoplanet weather. JWST will sample a diverse population of planets of varying masses and densities in a wide variety of environments characterized by a range of host star masses and metallicities, orbital semi-major axes and eccentricities. A broad program of exoplanet science could use a substantial fraction of the overall JWST mission. △ Less

Submitted 6 November, 2014; originally announced November 2014.

Comments: Summary of a workshop held in Pasadena, CA, in March 2014

A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b

Authors: Laura Kreidberg, Jacob L. Bean, Jean-Michel Désert, Michael R. Line, Jonathan J. Fortney, Nikku Madhusudhan, Kevin B. Stevenson, Adam P. Showman, David Charbonneau, Peter R. McCullough, Sara Seager, Adam Burrows, Gregory W. Henry, Michael Williamson, Tiffany Kataria, Derek Homeier

Abstract: The water abundance in a planetary atmosphere provides a key constraint on the planet's primordial origins because water ice is expected to play an important role in the core accretion model of planet formation. However, the water content of the Solar System giant planets is not well known because water is sequestered in clouds deep in their atmospheres. By contrast, short-period exoplanets have s… ▽ More The water abundance in a planetary atmosphere provides a key constraint on the planet's primordial origins because water ice is expected to play an important role in the core accretion model of planet formation. However, the water content of the Solar System giant planets is not well known because water is sequestered in clouds deep in their atmospheres. By contrast, short-period exoplanets have such high temperatures that their atmospheres have water in the gas phase, making it possible to measure the water abundance for these objects. We present a precise determination of the water abundance in the atmosphere of the 2 $M_\mathrm{Jup}$ short-period exoplanet WASP-43b based on thermal emission and transmission spectroscopy measurements obtained with the Hubble Space Telescope. We find the water content is consistent with the value expected in a solar composition gas at planetary temperatures (0.4-3.5x solar at 1 $σ$ confidence). The metallicity of WASP-43b's atmosphere suggested by this result extends the trend observed in the Solar System of lower metal enrichment for higher planet masses. △ Less

Submitted 8 October, 2014; originally announced October 2014.

Comments: Accepted to ApJL; this version contains three supplemental figures that are not included in the published paper. See also our companion paper "Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy" by Stevenson et al

Journal ref: ApJ, 793, L27, 2014

Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy

Authors: Kevin B. Stevenson, Jean-Michel Desert, Michael R. Line, Jacob L. Bean, Jonathan J. Fortney, Adam P. Showman, Tiffany Kataria, Laura Kreidberg, Peter R. McCullough, Gregory W. Henry, David Charbonneau, Adam Burrows, Sara Seager, Nikku Madhusudhan, Michael H. Williamson, Derek Homeier

Abstract: Exoplanets that orbit close to their host stars are much more highly irradiated than their Solar System counterparts. Understanding the thermal structures and appearances of these planets requires investigating how their atmospheres respond to such extreme stellar forcing. We present spectroscopic thermal emission measurements as a function of orbital phase ("phase-curve observations") for the hig… ▽ More Exoplanets that orbit close to their host stars are much more highly irradiated than their Solar System counterparts. Understanding the thermal structures and appearances of these planets requires investigating how their atmospheres respond to such extreme stellar forcing. We present spectroscopic thermal emission measurements as a function of orbital phase ("phase-curve observations") for the highly-irradiated exoplanet WASP-43b spanning three full planet rotations using the Hubble Space Telescope. With these data, we construct a map of the planet's atmospheric thermal structure, from which we find large day-night temperature variations at all measured altitudes and a monotonically decreasing temperature with pressure at all longitudes. We also derive a Bond albedo of 0.18 +0.07,-0.12 and an altitude dependence in the hot-spot offset relative to the substellar point. △ Less

Submitted 8 October, 2014; originally announced October 2014.

Comments: 28 pages, 12 figures, 1 movie, includes supplementary materials, accepted for publication in Science. Also see two companion papers titled "A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b" by Kreidberg et al. (2014b) and "The atmospheric circulation of the hot Jupiter WASP-43b: Comparing three-dimensional models to spectrophotometric data" by Kataria et al. (2014)

Water vapor in the spectrum of the extrasolar planet HD 189733b: 2. The eclipse

Authors: Nicolas Crouzet, Peter R. McCullough, Drake Deming, Nikku Madhusudhan

Abstract: Spectroscopic observations of exoplanets are crucial to infer the composition and properties of their atmospheres. HD 189733b is one of the most extensively studied exoplanets and is a corner stone for hot Jupiter models. In this paper, we report the day-side emission spectrum of HD 189733b in the wavelength range 1.1 to 1.7 $μ$m obtained with the Hubble Space Telescope Wide Field Camera 3 in spat… ▽ More Spectroscopic observations of exoplanets are crucial to infer the composition and properties of their atmospheres. HD 189733b is one of the most extensively studied exoplanets and is a corner stone for hot Jupiter models. In this paper, we report the day-side emission spectrum of HD 189733b in the wavelength range 1.1 to 1.7 $μ$m obtained with the Hubble Space Telescope Wide Field Camera 3 in spatial scan mode. The quality of the data is such that even a straightforward analysis yields a high precision Poisson noise limited spectrum: the median 1-$σ$ uncertainty is 57 ppm per 0.02 $μ$m bin. We also build a white-light curve correcting for systematic effects and derive an absolute eclipse depth of 96$\pm$39 ppm. The resulting spectrum shows marginal evidence for water vapor absorption, but can also be well explained by a blackbody spectrum. However, the combination of these WFC3 data with previous Spitzer photometric observations is best explained by a day-side atmosphere of HD 189733b with no thermal inversion and a nearly solar or sub-solar H$_2$O abundance in a cloud-free atmosphere. Alternatively, this apparent sub-solar abundance may be the result of clouds or hazes which future studies need to investigate. △ Less

Submitted 20 September, 2014; v1 submitted 13 September, 2014; originally announced September 2014.

Comments: Accepted for publication in ApJ

H2O abundances in the atmospheres of three hot Jupiters

Authors: Nikku Madhusudhan, Nicolas Crouzet, Peter R. McCullough, Drake Deming, Christina Hedges

Abstract: The core accretion theory for giant planet formation predicts enrichment of elemental abundances in planetary envelopes caused by runaway accretion of planetesimals, which is consistent with measured super-solar abundances of C, N, P, S, Xe, and Ar in Jupiter's atmosphere. However, the abundance of O which is expected to be the most dominant constituent of planetesimals is unknown for solar system… ▽ More The core accretion theory for giant planet formation predicts enrichment of elemental abundances in planetary envelopes caused by runaway accretion of planetesimals, which is consistent with measured super-solar abundances of C, N, P, S, Xe, and Ar in Jupiter's atmosphere. However, the abundance of O which is expected to be the most dominant constituent of planetesimals is unknown for solar system giant planets, owing to the condensation of water in their ultra-cold atmospheres, thereby posing a key unknown in solar system formation. On the other hand, hundreds of extrasolar hot Jupiters are known with very high temperatures (>~1000 K) making them excellent targets to measure H2O abundances and, hence, oxygen in their atmospheres. We constrain the atmospheric H2O abundances in three hot Jupiters (HD 189733b, HD 209458b, and WASP-12b), spanning a wide temperature range (1200-2500 K), using their near-infrared transmission spectra obtained using the HST WFC3 instrument. We report conclusive measurements of H2O in HD 189733b and HD 209458b, while that in WASP-12b is not well constrained by present data. The data allow nearly solar as well as significantly sub-solar abundances in HD 189733b and WASP-12b. However, for HD 209458b, we report the most precise H2O measurement in an exoplanet to date that suggests a ~20-135 sub-solar H2O abundance. We discuss the implications of our results on the formation conditions of hot Jupiters and on the likelihood of clouds in their atmospheres. Our results highlight the critical importance of high-precision spectra of hot Jupiters for deriving their H2O abundances. △ Less

Submitted 22 July, 2014; originally announced July 2014.

Comments: ApJ Letters, in press

Water Vapor in the Spectrum of the Extrasolar Planet HD 189733b: 1. the Transit

Authors: P. R. McCullough, N. Crouzet, D. Deming, N. Madhusudhan

Abstract: We report near-infrared spectroscopy of the gas giant planet HD 189733b in transit. We used the Hubble Space Telescope Wide Field Camera 3 (HST WFC3) with its G141 grism covering 1.1 um to 1.7 um and spatially scanned the image across the detector at 2\arcsec$s^{-1}$. When smoothed to 75 nm bins, the local maxima of the transit depths in the 1.15 um and 1.4 um water vapor features respectively are… ▽ More We report near-infrared spectroscopy of the gas giant planet HD 189733b in transit. We used the Hubble Space Telescope Wide Field Camera 3 (HST WFC3) with its G141 grism covering 1.1 um to 1.7 um and spatially scanned the image across the detector at 2\arcsec$s^{-1}$. When smoothed to 75 nm bins, the local maxima of the transit depths in the 1.15 um and 1.4 um water vapor features respectively are 83+/-53 ppm and 200+/-47 ppm greater than the local minimum at 1.3 um. We compare the WFC3 spectrum with the composite transit spectrum of HD 189733b assembled by Pont et al. (2013), extending from 0.3 um to 24 um. Although the water vapor features in the WFC3 spectrum are compatible with the model of non-absorbing, Rayleigh-scattering dust in the planetary atmosphere (Pont et al. 2013), we also re-interpret the available data with a clear planetary atmosphere. In the latter interpretation, the slope of increasing transit depth with shorter wavelengths from the near infrared, through the visible and into the ultraviolet is caused by unocculted star spots, with a smaller contribution of Rayleigh scattering by molecular hydrogen in the planet's atmosphere. At relevant pressures along the terminator, our model planetary atmosphere's temperature is ~700 K, which is below the condensation temperatures of sodium- and potassium-bearing molecules, causing the broad wings of the spectral lines of Na I and K I at 0.589 um and 0.769 um to be weak. △ Less

Submitted 9 July, 2014; originally announced July 2014.

Comments: 14 pages, 5 figures, Accepted to ApJ

Transit and Radial Velocity Survey Efficiency Comparison for a Habitable Zone Earth

Authors: Christopher J. Burke, P. R. McCullough

Abstract: Transit and radial velocity searches are two techniques for identifying nearby extrasolar planets to Earth that transit bright stars. Identifying a robust sample of these exoplanets around bright stars for detailed atmospheric characterization is a major observational undertaking. In this study we describe a framework that answers the question of whether a transit or radial velocity survey is more… ▽ More Transit and radial velocity searches are two techniques for identifying nearby extrasolar planets to Earth that transit bright stars. Identifying a robust sample of these exoplanets around bright stars for detailed atmospheric characterization is a major observational undertaking. In this study we describe a framework that answers the question of whether a transit or radial velocity survey is more efficient at finding transiting exoplanets given the same amount of observing time. Within the framework we show that a transit survey's window function can be approximated using the hypergeometric probability distribution. We estimate the observing time required for a transit survey to find a transiting Earth-sized exoplanet in the HZ with an emphasis on late type stars. We also estimate the radial velocity precision necessary to detect the equivalent HZ Earth-mass exoplanet that also transits when using an equal amount of observing time as the transit survey. We find that a radial velocity survey with sig_rv~0.6 m/s precision has comparable efficiency in terms of observing time to a transit survey with the requisite photometric precision sig_phot~300 ppm to find a transiting Earth-sized exoplanet in the HZ of late M~dwarfs. For Super-Earths, a sig_rv~2.0 m/s precision radial velocity survey has comparable efficiency to a transit survey with sig_phot~2300 ppm. △ Less

Submitted 24 June, 2014; originally announced June 2014.

Comments: 12 Pages, 9 Figures, Submitted ApJ

The Transiting Exoplanet Survey Satellite

Authors: George R. Ricker, Joshua N. Winn, Roland Vanderspek, David W. Latham, Gaspar A. Bakos, Jacob L. Bean, Zachory K. Berta-Thompson, Timothy M. Brown, Lars Buchhave, Nathaniel R. Butler, R. Paul Butler, William J. Chaplin, David Charbonneau, Jorgen Christensen-Dalsgaard, Mark Clampin, Drake Deming, John Doty, Nathan De Lee, Courtney Dressing, E. W. Dunham, Michael Endl, Francois Fressin, Jian Ge, Thomas Henning, Matthew J. Holman , et al. (33 additional authors not shown)

Abstract: The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-s… ▽ More The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I = 4-13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations. △ Less

Submitted 28 October, 2014; v1 submitted 1 June, 2014; originally announced June 2014.

Comments: accepted for publication in the new, peer-reviewed SPIE Journal of Astronomical Telescopes, Instruments, and Systems (JATIS)

Journal ref: GR Ricker, JN Winn, R Vanderspek et al.; "Transiting Exoplanet Survey Satellite," J. Astron. Telesc. Instrum. Syst., 1(1), 014003 (2015)

Hubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b

Authors: Heather A. Knutson, Diana Dragomir, Laura Kreidberg, Eliza M. -R. Kempton, P. R. McCullough, Jonathan J. Fortney, Jacob L. Bean, Michael Gillon, Derek Homeier, Andrew W. Howard

Abstract: Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad ra… ▽ More Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad range of bulk compositions, including both water-dominated worlds and rocky planets covered by a thick hydrogen and helium atmosphere. Measurements of the transmission spectra of these planets offer the opportunity to resolve this degeneracy by directly constraining the scale heights and corresponding mean molecular weights of their atmospheres. We present Hubble Space Telescope near-infrared spectroscopy of two transits of the newly discovered transiting super-Earth HD 97658b. We use the Wide Field Camera 3's scanning mode to measure the wavelength-dependent transit depth in thirty individual bandpasses. Our averaged differential transmission spectrum has a median 1 sigma uncertainty of 23 ppm in individual bins, making this the most precise observation of an exoplanetary transmission spectrum obtained with WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity atmosphere at the 10 sigma level. They are consistent at the 0.4 sigma level with a flat line model, as well as effectively flat models corresponding to a metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze layer located at pressures of 10 mbar or higher. △ Less

Submitted 27 August, 2014; v1 submitted 18 March, 2014; originally announced March 2014.

Comments: ApJ in press; revised version includes an updated orbital ephemeris for the planet

Kepler-413b: a slightly misaligned, Neptune-size transiting circumbinary planet

Authors: Veselin B. Kostov, Peter R. McCullough, Joshua A. Carter, Magali Deleuil, Rodrigo F. Diaz, Daniel C. Fabrycky, Guillaume Hebrard, Tobias C. Hinse, Tsevi Mazeh, Jerome A. Orosz, Zlatan I. Tsvetanov, William F. Welsh

Abstract: We report the discovery of a transiting, Rp = 4.347+/-0.099REarth, circumbinary planet (CBP) orbiting the Kepler K+M Eclipsing Binary (EB) system KIC 12351927 (Kepler-413) every ~66 days on an eccentric orbit with ap = 0.355+/-0.002AU, ep = 0.118+/-0.002. The two stars, with MA = 0.820+/-0.015MSun, RA = 0.776+/-0.009RSun and MB = 0.542+/-0.008MSun, RB = 0.484+/-0.024RSun respectively revolve aroun… ▽ More We report the discovery of a transiting, Rp = 4.347+/-0.099REarth, circumbinary planet (CBP) orbiting the Kepler K+M Eclipsing Binary (EB) system KIC 12351927 (Kepler-413) every ~66 days on an eccentric orbit with ap = 0.355+/-0.002AU, ep = 0.118+/-0.002. The two stars, with MA = 0.820+/-0.015MSun, RA = 0.776+/-0.009RSun and MB = 0.542+/-0.008MSun, RB = 0.484+/-0.024RSun respectively revolve around each other every 10.11615+/-0.00001 days on a nearly circular (eEB = 0.037+/-0.002) orbit. The orbital plane of the EB is slightly inclined to the line of sight (iEB = 87.33+/-0.06 degrees) while that of the planet is inclined by ~2.5 degrees to the binary plane at the reference epoch. Orbital precession with a period of ~11 years causes the inclination of the latter to the sky plane to continuously change. As a result, the planet often fails to transit the primary star at inferior conjunction, causing stretches of hundreds of days with no transits (corresponding to multiple planetary orbital periods). We predict that the next transit will not occur until 2020. The orbital configuration of the system places the planet slightly closer to its host stars than the inner edge of the extended habitable zone. Additionally, the orbital configuration of the system is such that the CBP may experience Cassini-States dynamics under the influence of the EB, in which the planet's obliquity precesses with a rate comparable to its orbital precession. Depending on the angular precession frequency of the CBP, it could potentially undergo obliquity fluctuations of dozens of degrees (and complex seasonal cycles) on precession timescales. △ Less

Submitted 28 January, 2014; originally announced January 2014.

Comments: 48 pages, 13 figures

The Emergent 1.1-1.7 Micron Spectrum of the Exoplanet CoRoT-2b as Measured Using the Hubble Space Telescope

Authors: Ashlee Wilkins, Drake Deming, Nikku Madhusudhan, Adam Burrows, Heather Knutson, Peter McCullough, Sukrit Ranjan

Abstract: We have used Hubble/WFC3 and the G141 grism to measure the secondary eclipse of the transiting very hot Jupiter CoRoT-2b in the 1.1-1.7$μ$m spectral region. We find an eclipse depth averaged over this band equal to $395^{+69}_{-45}$ parts per million, equivalent to a blackbody temperature of $1788\pm18$K. We study and characterize several WFC3 instrumental effects, especially the "hook" phenomenon… ▽ More We have used Hubble/WFC3 and the G141 grism to measure the secondary eclipse of the transiting very hot Jupiter CoRoT-2b in the 1.1-1.7$μ$m spectral region. We find an eclipse depth averaged over this band equal to $395^{+69}_{-45}$ parts per million, equivalent to a blackbody temperature of $1788\pm18$K. We study and characterize several WFC3 instrumental effects, especially the "hook" phenomenon described by Deming et al. (2013). We use data from several transiting exoplanet systems to find a quantitative relation between the amplitude of the hook and the exposure level of a given pixel. Although the uncertainties in this relation are too large to allow us to develop an empirical correction for our data, our study provides a useful guide for optimizing exposure levels in future WFC3 observations. We derive the planet's spectrum using a differential method. The planet-to-star contrast increases to longer wavelength within the WFC3 bandpass, but without water absorption or emission to a $3σ$ limit of 85 ppm. The slope of the WFC3 spectrum is significantly less than the slope of the best-fit blackbody. We compare all existing eclipse data for this planet to a blackbody spectrum, and to spectra from both solar abundance and carbon-rich (C/O=1) models. A blackbody spectrum is an acceptable fit to the full dataset. Extra continuous opacity due to clouds or haze, and flattened temperature profiles, are strong candidates to produce quasi-blackbody spectra, and to account for the amplitude of the optical eclipses. Our results show ambiguous evidence for a temperature inversion in this planet. △ Less

Submitted 17 January, 2014; originally announced January 2014.

Comments: 18 pages, 14 figures. Accepted for publication in ApJ on 1/16/2014

The Hubble Space Telescope Treasury Program on the Orion Nebula Cluster

Authors: M. Robberto, D. R. Soderblom, E. Bergeron, V. Kozhurina-Platais, R. B. Makidon, P. R. McCullough, M. McMaster, N. Panagia, I. N. Reid, Z. Levay, L. Frattare, N. Da Rio, M. Andersen, C. R. O'Dell, K. G. Stassun, M. Simon, E. D. Feigelson, J. R. Stauffer, M. Meyer, M. Reggiani, J. Krist, C. F. Manara, M. Romaniello, L. A. Hillenbrand, L. Ricci , et al. (5 additional authors not shown)

Abstract: The Hubble Space Telescope (HST) Treasury Program on the Orion Nebula Cluster has used 104 orbits of HST time to image the Great Orion Nebula region with the Advanced Camera for Surveys (ACS), the Wide-Field/Planetary Camera 2 (WFPC2) and the Near Infrared Camera and Multi Object Spectrograph (NICMOS) instruments in 11 filters ranging from the U-band to the H-band equivalent of HST. The program ha… ▽ More The Hubble Space Telescope (HST) Treasury Program on the Orion Nebula Cluster has used 104 orbits of HST time to image the Great Orion Nebula region with the Advanced Camera for Surveys (ACS), the Wide-Field/Planetary Camera 2 (WFPC2) and the Near Infrared Camera and Multi Object Spectrograph (NICMOS) instruments in 11 filters ranging from the U-band to the H-band equivalent of HST. The program has been intended to perform the definitive study of the stellar component of the ONC at visible wavelengths, addressing key questions like the cluster IMF, age spread, mass accretion, binarity and cirumstellar disk evolution. The scanning pattern allowed to cover a contiguous field of approximately 600 square arcminutes with both ACS and WFPC2, with a typical exposure time of approximately 11 minutes per ACS filter, corresponding to a point source depth AB(F435W) = 25.8 and AB(F775W)=25.2 with 0.2 magnitudes of photometric error. We describe the observations, data reduction and data products, including images, source catalogs and tools for quick look preview. In particular, we provide ACS photometry for 3399 stars, most of them detected at multiple epochs, WFPC2 photometry for 1643 stars, 1021 of them detected in the U-band, and NICMOS JH photometry for 2116 stars. We summarize the early science results that have been presented in a number of papers. The final set of images and the photometric catalogs are publicly available through the archive as High Level Science Products at the STScI Multimission Archive hosted by the Space Telescope Science Institute. △ Less

Submitted 17 April, 2013; originally announced April 2013.

Comments: Accepted for publication on the Astrophysical Journal Supplement Series, March 27, 2013

Infrared Transmission Spectroscopy of the Exoplanets HD209458b and XO-1b Using the Wide Field Camera-3 on the Hubble Space Telescope

Authors: Drake Deming, Ashlee Wilkins, Peter McCullough, Adam Burrows, Jonathan J. Fortney, Eric Agol, Ian Dobbs-Dixon, Nikku Madhusudhan, Nicolas Crouzet, Jean-Michel Desert, Ronald L. Gilliland, Korey Haynes, Heather A. Knutson, Michael Line, Zazralt Magic, Avi M. Mandell, Sukrit Ranjan, David Charbonneau, Mark Clampin, Sara Seager, Adam P. Showman

Abstract: Exoplanetary transmission spectroscopy in the near-infrared using Hubble/NICMOS is currently ambiguous because different observational groups claim different results from the same data, depending on their analysis methodologies. Spatial scanning with Hubble/WFC3 provides an opportunity to resolve this ambiguity. We here report WFC3 spectroscopy of the giant planets HD209458b and XO-1b in transit,… ▽ More Exoplanetary transmission spectroscopy in the near-infrared using Hubble/NICMOS is currently ambiguous because different observational groups claim different results from the same data, depending on their analysis methodologies. Spatial scanning with Hubble/WFC3 provides an opportunity to resolve this ambiguity. We here report WFC3 spectroscopy of the giant planets HD209458b and XO-1b in transit, using spatial scanning mode for maximum photon-collecting efficiency. We introduce an analysis technique that derives the exoplanetary transmission spectrum without the necessity of explicitly decorrelating instrumental effects, and achieves nearly photon-limited precision even at the high flux levels collected in spatial scan mode. Our errors are within 6-percent (XO-1) and 26-percent (HD209458b) of the photon-limit at a spectral resolving power of 70, and are better than 0.01-percent per spectral channel. Both planets exhibit water absorption of approximately 200 ppm at the water peak near 1.38 microns. Our result for XO-1b contradicts the much larger absorption derived from NICMOS spectroscopy. The weak water absorption we measure for HD209458b is reminiscent of the weakness of sodium absorption in the first transmission spectroscopy of an exoplanet atmosphere by Charbonneau et al. (2002). Model atmospheres having uniformly-distributed extra opacity of 0.012 cm^2 per gram account approximately for both our water measurement and the sodium absorption in this planet. Our results for HD209458b support the picture advocated by Pont et al. (2013) in which weak molecular absorptions are superposed on a transmission spectrum that is dominated by continuous opacity due to haze and/or dust. However, the extra opacity needed for HD209458b is grayer than for HD189733b, with a weaker Rayleigh component. △ Less

Submitted 12 July, 2013; v1 submitted 5 February, 2013; originally announced February 2013.

Comments: new figures, one new table, minor text revisions, accepted for ApJ

Transmission spectroscopy of exoplanet XO-2b observed with HST NICMOS

Authors: Nicolas Crouzet, Peter R. McCullough, Christopher J. Burke, Douglas Long

Abstract: Spectroscopy during planetary transits is a powerful tool to probe exoplanet atmospheres. We present the near-infrared transit spectroscopy of XO-2b obtained with HST NICMOS. Uniquely for NICMOS transit spectroscopy, a companion star of similar properties to XO-2 is present in the field of view. We derive improved star and planet parameters through a photometric white-light analysis. We show a cle… ▽ More Spectroscopy during planetary transits is a powerful tool to probe exoplanet atmospheres. We present the near-infrared transit spectroscopy of XO-2b obtained with HST NICMOS. Uniquely for NICMOS transit spectroscopy, a companion star of similar properties to XO-2 is present in the field of view. We derive improved star and planet parameters through a photometric white-light analysis. We show a clear correlation of the spectrum noise with instrumental parameters, in particular the angle of the spectral trace on the detector. An MCMC method using a decorrelation from instrumental parameters is used to extract the planetary spectrum. Spectra derived independently from each of the 3 visits have a RMS of 430, 510, and 1000 ppm respectively. The same analysis is performed on the companion star after numerical injection of a transit with a depth constant at all wavelengths. The extracted spectra exhibit residuals of similar amplitude as for XO-2, which represent the level of remaining NICMOS systematics. This shows that extracting planetary spectra is at the limit of NICMOS' capability. We derive a spectrum for the planet XO-2b using the companion star as a reference. The derived spectrum can be represented by a theoretical model including atmospheric water vapor or by a flat spectrum model. We derive a 3-sigma upper limit of 1570 ppm on the presence of water vapor absorption in the atmosphere of XO-2b. In an appendix, we perform a similar analysis for the gas giant planet XO-1b. △ Less

Submitted 18 October, 2012; originally announced October 2012.

Comments: 35 pages, 18 figures, accepted (ApJ)

A Gas Giant Circumbinary Planet Transiting the F Star Primary of the Eclipsing Binary Star KIC 4862625 and the Independent Discovery and Characterization of the two transiting planets in the Kepler-47 System

Authors: Veselin B. Kostov, Peter McCullough, Tobias Hinse, Zlatan Tsvetanov, Guillaume Hébrard, Rodrigo Díaz, Magali Deleuil, Jeff A. Valenti

Abstract: We report the discovery of a transiting, gas giant circumbinary planet orbiting the eclipsing binary KIC 4862625 and describe our independent discovery of the two transiting planets orbiting Kepler-47 (Orosz et al. 2012). We describe a simple and semi-automated procedure for identifying individual transits in light curves and present our follow-up measurements of the two circumbinary systems. For… ▽ More We report the discovery of a transiting, gas giant circumbinary planet orbiting the eclipsing binary KIC 4862625 and describe our independent discovery of the two transiting planets orbiting Kepler-47 (Orosz et al. 2012). We describe a simple and semi-automated procedure for identifying individual transits in light curves and present our follow-up measurements of the two circumbinary systems. For the KIC 4862625 system, the 0.52+/-0.018 RJup radius planet revolves every ~138 days and occults the 1.47+/-0.08 MSun, 1.7 +/-0.06 RSun F8 IV primary star producing aperiodic transits of variable durations commensurate with the configuration of the eclipsing binary star. Our best-fit model indicates the orbit has a semi-major axis of 0.64 AU and is slightly eccentric, e=0.1. For the Kepler-47 system, we confirm the results of Orosz et al. (2012). Modulations in the radial velocity of KIC 4862625A are measured both spectroscopically and photometrically, i.e. via Doppler boosting, and produce similar results. △ Less

Submitted 19 April, 2013; v1 submitted 14 October, 2012; originally announced October 2012.

Comments: 40 pages, 17 figures

The Flat Transmission Spectrum of the Super-Earth GJ1214b from Wide Field Camera 3 on the Hubble Space Telescope

Authors: Zachory K. Berta, David Charbonneau, Jean-Michel Désert, Eliza Miller-Ricci Kempton, Peter R. McCullough, Christopher J. Burke, Jonathan J. Fortney, Jonathan Irwin, Philip Nutzman, Derek Homeier

Abstract: Capitalizing on the observational advantage offered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the transmission spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, findin… ▽ More Capitalizing on the observational advantage offered by its tiny M dwarf host, we present HST/WFC3 grism measurements of the transmission spectrum of the super-Earth exoplanet GJ1214b. These are the first published WFC3 observations of a transiting exoplanet atmosphere. After correcting for a ramp-like instrumental systematic, we achieve nearly photon-limited precision in these observations, finding the transmission spectrum of GJ1214b to be flat between 1.1 and 1.7 microns. Inconsistent with a cloud-free solar composition atmosphere at 8.2 sigma, the measured achromatic transit depth most likely implies a large mean molecular weight for GJ1214b's outer envelope. A dense atmosphere rules out bulk compositions for GJ1214b that explain its large radius by the presence of a very low density gas layer surrounding the planet. High-altitude clouds can alternatively explain the flat transmission spectrum, but they would need to be optically thick up to 10 mbar or consist of particles with a range of sizes approaching 1 micron in diameter. △ Less

Submitted 23 November, 2011; originally announced November 2011.

Comments: 17 pages, 12 figures, accepted for publication in ApJ

Precise Estimates of the Physical Parameters for the Exoplanet System HD-17156 Enabled by HST FGS Transit and Asteroseismic Observations

Authors: Philip Nutzman, Ronald L. Gilliland, Peter R. McCullough, David Charbonneau, Jørgen Christensen-Dalsgaard, Hans Kjeldsen, Edmund P. Nelan, Timothy M. Brown, Matthew J. Holman

Abstract: We present observations of three distinct transits of HD 17156b obtained with the Fine Guidance Sensors (FGS) on board the Hubble Space Telescope} (HST). We analyzed both the transit photometry and previously published radial velocities to find the planet-star radius ratio R_p/R_s = 0.07454 +/- 0.00035, inclination i=86.49 +0.24/-0.20 deg, and scaled semi-major axis a/R = 23.19 +0.32/-0.27. This l… ▽ More We present observations of three distinct transits of HD 17156b obtained with the Fine Guidance Sensors (FGS) on board the Hubble Space Telescope} (HST). We analyzed both the transit photometry and previously published radial velocities to find the planet-star radius ratio R_p/R_s = 0.07454 +/- 0.00035, inclination i=86.49 +0.24/-0.20 deg, and scaled semi-major axis a/R = 23.19 +0.32/-0.27. This last value translates directly to a mean stellar density determination of 0.522 +0.021/-0.018 g cm^-3. Analysis of asteroseismology observations by the companion paper of Gilliland et al. (2009) provides a consistent but significantly refined measurement of the stellar mean density. We compare stellar isochrones to this density estimate and find M_s = 1.275 +/- 0.018 M_sun and a stellar age of $3.37 +0.20/-0.47 Gyr. Using this estimate of M_s and incorporating the density constraint from asteroseismology, we model both the photometry and published radial velocities to estimate the planet radius R_p= 1.0870 +/- 0.0066 Jupiter radii and the stellar radius R_s = 1.5007 +/- 0.0076 R_sun. The planet radius is larger than that found in previous studies and consistent with theoretical models of a solar-composition gas giant of the same mass and equilibrium temperature. For the three transits, we determine the times of mid-transit to a precision of 6.2 s, 7.6 s, and 6.9 s, and the transit times for HD 17156 do not show any significant departures from a constant period. The joint analysis of transit photometry and asteroseismology presages similar studies that will be enabled by the NASA Kepler Mission. △ Less

Submitted 1 November, 2010; originally announced November 2010.

Comments: Accepted for publication to ApJ

Asteroseismology of the Transiting Exoplanet Host HD 17156 with HST FGS

Authors: Ronald L. Gilliland, Peter R. McCullough, Edmund P. Nelan, Timothy M. Brown, David Charbonneau, Philip Nutzman, Joergen Christensen-Dalsgaard, Hans Kjeldsen

Abstract: Observations conducted with the Fine Guidance Sensor on Hubble Space Telescope (HST) providing high cadence and precision time-series photometry were obtained over 10 consecutive days in December 2008 on the host star of the transiting exoplanet HD 17156b. During this time 10^12 photons (corrected for detector deadtime) were collected in which a noise level of 163 parts per million per 30 second s… ▽ More Observations conducted with the Fine Guidance Sensor on Hubble Space Telescope (HST) providing high cadence and precision time-series photometry were obtained over 10 consecutive days in December 2008 on the host star of the transiting exoplanet HD 17156b. During this time 10^12 photons (corrected for detector deadtime) were collected in which a noise level of 163 parts per million per 30 second sum resulted, thus providing excellent sensitivity to detection of the analog of the solar 5-minute p-mode oscillations. For HD 17156 robust detection of p-modes supports determination of the stellar mean density of 0.5301 +/- 0.0044 g/cm^3 from a detailed fit to the observed frequencies of modes of degree l = 0, 1, and 2. This is the first star for which direct determination of the mean stellar density has been possible using both asteroseismology and detailed analysis of a transiting planet light curve. Using the density constraint from asteroseismology, and stellar evolution modeling results in M_star = 1.285 +/- 0.026 solar, R_star = 1.507 +/- 0.012 solar, and a stellar age of 3.2 +/- 0.3 Gyr. △ Less

Submitted 1 November, 2010; originally announced November 2010.

Comments: Accepted by ApJ; 16 pages, 18 figures

The XO Planetary Survey Project - Astrophysical False Positives

Authors: Radosław Poleski, Peter R. McCullough, Jeff A. Valenti, Christopher J. Burke, Pavel Machalek, Kenneth Janes

Abstract: Searches for planetary transits find many astrophysical false positives as a by-product. There are four main types analyzed in the literature: a grazing-incidence eclipsing binary star, an eclipsing binary star with a small radius companion star, a blend of one or more stars with an unrelated eclipsing binary star, and a physical triple star system. We present a list of 69 astrophysical false posi… ▽ More Searches for planetary transits find many astrophysical false positives as a by-product. There are four main types analyzed in the literature: a grazing-incidence eclipsing binary star, an eclipsing binary star with a small radius companion star, a blend of one or more stars with an unrelated eclipsing binary star, and a physical triple star system. We present a list of 69 astrophysical false positives that had been identified as candidates of transiting planets of the on-going XO survey. This list may be useful in order to avoid redundant observation and characterization of these particular candidates independently identified by other wide-field searches for transiting planets. The list may be useful for those modeling the yield of the XO survey and surveys similar to it. Subsequent observations of some of the listed stars may improve mass-radius relations, especially for low-mass stars. From the candidates exhibiting eclipses, we report three new spectroscopic double-line binaries and give mass function estimations for 15 single lined spectroscopic binaries. △ Less

Submitted 10 June, 2010; originally announced June 2010.

Comments: 13 pages, 4 figures, accepted to ApJS

NICMOS Observations of the Transiting Hot Jupiter XO-1b

Authors: Christopher J. Burke, P. R. McCullough, E. Bergeron, Douglas Long, Ronald L. Gilliland, Edmund P. Nelan, Christopher M. Johns-Krull, Jeff A. Valenti, Kenneth A. Janes

Abstract: We refine the physical parameters of the transiting hot Jupiter planet XO-1b and its stellar host XO-1 using HST NICMOS observations. XO-1b has a radius Rp=1.21+/-0.03 RJup, and XO-1 has a radius Rs=0.94+/-0.02 RSun, where the uncertainty in the mass of XO-1 dominates the uncertainty of Rp and Rs. There are no significant differences in the XO-1 system properties between these broad-band NIR obser… ▽ More We refine the physical parameters of the transiting hot Jupiter planet XO-1b and its stellar host XO-1 using HST NICMOS observations. XO-1b has a radius Rp=1.21+/-0.03 RJup, and XO-1 has a radius Rs=0.94+/-0.02 RSun, where the uncertainty in the mass of XO-1 dominates the uncertainty of Rp and Rs. There are no significant differences in the XO-1 system properties between these broad-band NIR observations and previous determinations based upon ground-based optical observations. We measure two transit timings from these observations with 9 s and 15 s precision. As a residual to a linear ephemeris model, there is a 2.0 sigma timing difference between the two HST visits that are separated by 3 transit events (11.8 days). These two transit timings and additional timings from the literature are sufficient to rule out the presence of an Earth mass planet orbiting in 2:1 mean motion resonance coplanar with XO-1b. We identify and correct for poorly understood gain-like variations present in NICMOS time series data. This correction reduces the effective noise in time series photometry by a factor of two, for the case of XO-1. △ Less

Submitted 10 June, 2010; originally announced June 2010.

Comments: 13 pages, 8 figures, submitted to ApJ

Probing the terminator region atmosphere of the Hot-Jupiter XO-1b with transmission spectroscopy

Authors: G. Tinetti, P. Deroo, M. R. Swain, C. A. Griffith, G. Vasisht, L. R. Brown, C. Burke, P. McCullough

Abstract: We report here the first infrared spectrum of the hot-Jupiter XO-1b. The observations were obtained with NICMOS instrument onboard the Hubble Space Telescope during a primary eclipse of the XO-1 system. Near photon-noise-limited spectroscopy between 1.2 and 1.8 micron allows us to determine the main composition of this hot-Jupiter's planetary atmosphere with good precision. This is the third hot… ▽ More We report here the first infrared spectrum of the hot-Jupiter XO-1b. The observations were obtained with NICMOS instrument onboard the Hubble Space Telescope during a primary eclipse of the XO-1 system. Near photon-noise-limited spectroscopy between 1.2 and 1.8 micron allows us to determine the main composition of this hot-Jupiter's planetary atmosphere with good precision. This is the third hot-Jupiter's atmosphere for which spectroscopic data are available in the near IR. The spectrum shows the presence of water vapor (H2O), methane (CH4) and carbon dioxide (CO2), and suggests the possible presence of carbon monoxide (CO). We show that the published IRAC secondary transit emission photometric data are compatible with the atmospheric composition at the terminator determined from the NICMOS spectrum, with a range of possible mixing-ratios and thermal profiles; additional emission spectroscopy data are needed to reduce the degeneracy of the possible solutions. Finally, we note the similarity between the 1.2-1.8 micron transmission spectra of XO-1b and HD 209458b, suggesting that in addition to having similar stellar/orbital and planetary parameters the two systems may also have a similar exoplanetary atmospheric composition. △ Less

Submitted 12 February, 2010; originally announced February 2010.

Comments: ApJ accepted, 4 figures

Thermal Emission and Tidal Heating of the Heavy and Eccentric Planet XO-3b

Authors: Pavel Machalek, Tom Greene, Peter R. McCullough, Adam Burrows, Christopher J. Burke, Joseph L. Hora, Christopher M. Johns-Krull, Drake L. Deming

Abstract: We determined the flux ratios of the heavy and eccentric planet XO-3b to its parent star in the four IRAC bands of the Spitzer Space Telescope: 0.101% +- 0.004% at 3.6 micron; 0.143% +- 0.006% at 4.5 micron; 0.134% +- 0.049% at 5.8 micron and 0.150% +- 0.036% at 8.0 micron. The flux ratios are within [-2.2,0.3, -0.8, -1.7]-sigma of the model of XO-3b with a thermally inverted stratosphere in the… ▽ More We determined the flux ratios of the heavy and eccentric planet XO-3b to its parent star in the four IRAC bands of the Spitzer Space Telescope: 0.101% +- 0.004% at 3.6 micron; 0.143% +- 0.006% at 4.5 micron; 0.134% +- 0.049% at 5.8 micron and 0.150% +- 0.036% at 8.0 micron. The flux ratios are within [-2.2,0.3, -0.8, -1.7]-sigma of the model of XO-3b with a thermally inverted stratosphere in the 3.6 micron, 4.5 micron, 5.8 micron and 8.0 micron channels, respectively. XO-3b has a high illumination from its parent star (Fp ~(1.9 - 4.2) x 10^9 ergs cm^-2 s^-1) and is thus expected to have a thermal inversion, which we indeed observe. When combined with existing data for other planets, the correlation between the presence of an atmospheric temperature inversion and the substellar flux is insufficient to explain why some high insolation planets like TrES-3 do not have stratospheric inversions and some low insolation planets like XO-1b do have inversions. Secondary factors such as sulfur chemistry, atmospheric metallicity, amounts of macroscopic mixing in the stratosphere or even dynamical weather effects likely play a role. Using the secondary eclipse timing centroids we determined the orbital eccentricity of XO-3b as e = 0.277 +- 0.009. The model radius-age trajectories for XO-3b imply that at least some amount of tidal-heating is required to inflate the radius of XO-3b, and the tidal heating parameter of the planet is constrained to Qp < 10^6 . △ Less

Submitted 13 January, 2010; originally announced January 2010.

Comments: Accepted for publications in The Astrophysical Journal

Detection of Thermal Emission of XO-2b: Evidence for a Weak Temperature Inversion

Authors: Pavel Machalek, Peter R. McCullough, Adam Burrows, Christopher J. Burke, Joseph L. Hora, Christopher M. Johns-Krull

Abstract: We estimate flux ratios of the extrasolar planet XO-2b to its host star XO-2 at 3.6, 4.5, 5.8 and 8.0 micron with IRAC on the Spitzer Space Telescope to be 0.00081 +- 0.00017, 0.00098 +- 0.00020, 0.00167 +- 0.00036 and 0.00133 +- 0.00049, respectively. The fluxes provide tentative evidence for a weak temperature inversion in the upper atmosphere, the precise nature of which would need to be conf… ▽ More We estimate flux ratios of the extrasolar planet XO-2b to its host star XO-2 at 3.6, 4.5, 5.8 and 8.0 micron with IRAC on the Spitzer Space Telescope to be 0.00081 +- 0.00017, 0.00098 +- 0.00020, 0.00167 +- 0.00036 and 0.00133 +- 0.00049, respectively. The fluxes provide tentative evidence for a weak temperature inversion in the upper atmosphere, the precise nature of which would need to be confirmed by longer wavelength observations. XO-2b substellar flux of 0.76 x 10^9 ergs cm^-2 s^-1 lies in the predicted transition region between atmospheres with and without upper atmospheric temperature inversion. △ Less

Submitted 6 June, 2009; originally announced June 2009.

Comments: 17 pages. Accepted for publication in The Astrophysical Journal

Journal ref: Astrophys.J.701:514-520,2009

Advanced Technology Large-Aperture Space Telescope (ATLAST): A Technology Roadmap for the Next Decade

Authors: Marc Postman, Vic Argabright, Bill Arnold, David Aronstein, Paul Atcheson, Morley Blouke, Tom Brown, Daniela Calzetti, Webster Cash, Mark Clampin, Dave Content, Dean Dailey, Rolf Danner, Rodger Doxsey, Dennis Ebbets, Peter Eisenhardt, Lee Feinberg, Andrew Fruchter, Mauro Giavalisco, Tiffany Glassman, Qian Gong, James Green, John Grunsfeld, Ted Gull, Greg Hickey , et al. (43 additional authors not shown)

Abstract: The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a set of mission concepts for the next generation of UVOIR space observatory with a primary aperture diameter in the 8-m to 16-m range that will allow us to perform some of the most challenging observations to answer some of our most compelling questions, including "Is there life elsewhere in the Galaxy?" We have identified two d… ▽ More The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a set of mission concepts for the next generation of UVOIR space observatory with a primary aperture diameter in the 8-m to 16-m range that will allow us to perform some of the most challenging observations to answer some of our most compelling questions, including "Is there life elsewhere in the Galaxy?" We have identified two different telescope architectures, but with similar optical designs, that span the range in viable technologies. The architectures are a telescope with a monolithic primary mirror and two variations of a telescope with a large segmented primary mirror. This approach provides us with several pathways to realizing the mission, which will be narrowed to one as our technology development progresses. The concepts invoke heritage from HST and JWST design, but also take significant departures from these designs to minimize complexity, mass, or both. Our report provides details on the mission concepts, shows the extraordinary scientific progress they would enable, and describes the most important technology development items. These are the mirrors, the detectors, and the high-contrast imaging technologies, whether internal to the observatory, or using an external occulter. Experience with JWST has shown that determined competitors, motivated by the development contracts and flight opportunities of the new observatory, are capable of achieving huge advances in technical and operational performance while keeping construction costs on the same scale as prior great observatories. △ Less

Submitted 8 May, 2009; v1 submitted 6 April, 2009; originally announced April 2009.

Comments: 22 pages, RFI submitted to Astro2010 Decadal Committee

Photometric Detection of a Transit of HD 80606b

Authors: E. Garcia-Melendo, P. R. McCullough

Abstract: We report a times series of B-band photometric observations initiated on the eve of Valentine's day, February 14, 2009, at the anticipated time of a transit of the extrasolar planet HD 80606b. The same transit has been observed independently (Fossey et al. 2009; Moutou et al. 2009). For one transit model favored by the data, minimum light equals 0.990 times the nominal brightness of HD 80606 and… ▽ More We report a times series of B-band photometric observations initiated on the eve of Valentine's day, February 14, 2009, at the anticipated time of a transit of the extrasolar planet HD 80606b. The same transit has been observed independently (Fossey et al. 2009; Moutou et al. 2009). For one transit model favored by the data, minimum light equals 0.990 times the nominal brightness of HD 80606 and occurs at HJD 2454876.33. The latter time, combined with the orbital period $P = 111.4277 \pm 0.0032$ days, longitude of periastron, $ω= 300.4977 \pm 0.0045$ degrees, and time of mid-secondary eclipse HJD $2454424.736 \pm 0.003$ (Laughlin et al. 2009), refines the orbital eccentricity and inclination. The duration of the model transit is 0.47 days, and its four contacts occur at HJD 2454876 plus 0.10, 0.24, 0.42, and 0.57 days. We describe parameterizations of a transit model with mutually accommodating eccentricity, $e = 0.9337^{+0.0009}_{-0.0006}$, inclination, $i = 89.26^{+0.24}_{-0.09}$ degrees, and the planetary radius in units of the stellar radius \RpRs$ = 0.11^{+0.04}_{-0.02}$. △ Less

Submitted 13 March, 2009; v1 submitted 26 February, 2009; originally announced February 2009.

Comments: Accepted to ApJ, 4 pages, 4 figures. Analysis is more thorough than submitted version. Accepted version includes comparison to contemporaneous reports by others. Includes complete Table 1 in comments of Latex source. Corrects scale error in chi-squared. References updated

XO-4b: An Extrasolar Planet Transiting an F5V Star

Authors: P. R. McCullough, Christopher J. Burke, Jeff A. Valenti, Doug Long, Christopher M. Johns-Krull, P. Machalek, K. A. Janes, B. Taylor, J. Gregorio, C. N. Foote, Bruce L. Gary, M. Fleenor, Enrique García-Melendo, T. Vanmunster

Abstract: We report the discovery of the planet XO-4b, which transits the star XO-4 (GSC 03793-01994, V=10.7, F5V). Transits are 1.0% deep and 4.4 hours in duration. The star XO-4 has a mass of 1.32 M_sun.... The planet XO-4b has a mass of 1.72 M_Jup....radius of 1.34 R_Jup...orbital period 4.125 days. We analyze scintillation-limited differential R-band photometry of XO-4b in transit made with a 1.8-m te… ▽ More We report the discovery of the planet XO-4b, which transits the star XO-4 (GSC 03793-01994, V=10.7, F5V). Transits are 1.0% deep and 4.4 hours in duration. The star XO-4 has a mass of 1.32 M_sun.... The planet XO-4b has a mass of 1.72 M_Jup....radius of 1.34 R_Jup...orbital period 4.125 days. We analyze scintillation-limited differential R-band photometry of XO-4b in transit made with a 1.8-m telescope under photometric conditions, yielding photometric precision of 0.6 to 2.0 millimag per one-minute interval. The declination of XO-4 places it within the continuous viewing zone of the Hubble Space Telescope (HST), which permits observation without interruption caused by occultation by the Earth. Because the stellar rotation periods of the three hottest stars orbited by transiting gas-giant planets are 2.0, 1.1, and 2.0 times the planetary orbital periods, we note the possibility of resonant interaction. △ Less

Submitted 19 May, 2008; originally announced May 2008.

Comments: 27 pages, 7 figures, submitted to ApJ

Thermal Emission of Exoplanet XO-1b

Authors: Pavel Machalek, Peter R. McCullough, Christopher J. Burke, Jeff A. Valenti, Adam Burrows, Joseph L. Hora

Abstract: We estimate flux ratios of the extrasolar planet XO-1b to its host star XO-1 at 3.6, 4.5, 5.8 and 8.0 microns with the IRAC on the Spitzer Space Telescope to be 0.00086 +/- 0.00007, 0.00122 +/- 0.00009, 0.00261 +/- 0.00031 and 0.00210 +/- 0.00029, respectively. The fluxes are inconsistent with a canonical cloudless model for the thermal emission from a planet and suggest an atmosphere with a the… ▽ More We estimate flux ratios of the extrasolar planet XO-1b to its host star XO-1 at 3.6, 4.5, 5.8 and 8.0 microns with the IRAC on the Spitzer Space Telescope to be 0.00086 +/- 0.00007, 0.00122 +/- 0.00009, 0.00261 +/- 0.00031 and 0.00210 +/- 0.00029, respectively. The fluxes are inconsistent with a canonical cloudless model for the thermal emission from a planet and suggest an atmosphere with a thermal inversion layer and a possible stratospheric absorber. A newly emerging correlation between the presence of a thermal inversion layer in the planetary atmosphere and stellar insolation of the planet (Burrows et al. 2007b) is refined. The sub-stellar point flux from the parent star at XO-1b of ~ 0.49 x 10^9 erg cm^-2 s^-1 sets a new lower limit for the occurrence of a thermal inversion in a planetary atmosphere. △ Less

Submitted 16 May, 2008; originally announced May 2008.

Comments: 7 pages, 4 figures, 2 tables, accepted for publication to ApJ

Journal ref: 2008ApJ...684.1427M

XO-5b: A Transiting Jupiter-sized Planet With A Four Day Period

Authors: Christopher J. Burke, P. R. McCullough, Jeff A. Valenti, Doug Long, Christopher M. Johns-Krull, P. Machalek, Kenneth A. Janes, B. Taylor, Michael L. Fleenor, Cindy N. Foote, Bruce L. Gary, Enrique Garcia-Melendo, J. Gregorio, T. Vanmunster

Abstract: The star XO-5 (GSC 02959-00729, V=12.1, G8V) hosts a Jupiter-sized, Rp=1.15+/-0.12 Rjup, transiting extrasolar planet, XO-5b, with an orbital period of P=4.187732+/-0.00002 days. The planet mass (Mp=1.15+/-0.08 Mjup) and surface gravity (gp=22+/-5 m/s^2) are significantly larger than expected by empirical Mp-P and Mp-P-[Fe/H] relationships. However, the deviation from the Mp-P relationship for X… ▽ More The star XO-5 (GSC 02959-00729, V=12.1, G8V) hosts a Jupiter-sized, Rp=1.15+/-0.12 Rjup, transiting extrasolar planet, XO-5b, with an orbital period of P=4.187732+/-0.00002 days. The planet mass (Mp=1.15+/-0.08 Mjup) and surface gravity (gp=22+/-5 m/s^2) are significantly larger than expected by empirical Mp-P and Mp-P-[Fe/H] relationships. However, the deviation from the Mp-P relationship for XO-5b is not large enough to suggest a distinct type of planet as is suggested for GJ 436b, HAT-P-2b, and XO-3b. By coincidence XO-5 overlies the extreme H I plume that emanates from the interacting galaxy pair NGC 2444/NGC 2445 (Arp 143). △ Less

Submitted 15 May, 2008; originally announced May 2008.

Comments: 10 pages, 9 Figures, Submitted to ApJ

Journal ref: Astrophys.J.686:1331-1340,2008

The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b

Authors: Joshua N. Winn, Matthew J. Holman, Guillermo Torres, Peter McCullough, Christopher M. Johns-Krull, David W. Latham, Avi Shporer, Tsevi Mazeh, Enrique Garcia-Melendo, Cindy Foote, Gil Esquerdo, Mark Everett

Abstract: We present photometry of 13 transits of XO-3b, a massive transiting planet on an eccentric orbit. Previous data led to two inconsistent estimates of the planetary radius. Our data strongly favor the smaller radius, with increased precision: R_p = 1.217 +/- 0.073 R_Jup. A conflict remains between the mean stellar density determined from the light curve, and the stellar surface gravity determined… ▽ More We present photometry of 13 transits of XO-3b, a massive transiting planet on an eccentric orbit. Previous data led to two inconsistent estimates of the planetary radius. Our data strongly favor the smaller radius, with increased precision: R_p = 1.217 +/- 0.073 R_Jup. A conflict remains between the mean stellar density determined from the light curve, and the stellar surface gravity determined from the shapes of spectral lines. We argue the light curve should take precedence, and revise the system parameters accordingly. The planetary radius is about 1 sigma larger than the theoretical radius for a hydrogen-helium planet of the given mass and insolation. To help in planning future observations, we provide refined transit and occultation ephemerides. △ Less

Submitted 28 April, 2008; originally announced April 2008.

Comments: To appear in ApJ [22 pages]

Detecting "Temperate" Jupiters: The Prospects of Searching for Transiting Gas Giants in Habitability Zones

Authors: S. W. Fleming, S. R. Kane, P. R. McCullough, F. R. Chromey

Abstract: This paper investigates the effects of observing windows on detecting transiting planets by calculating the fraction of planets with a given period that have zero, one (single), two (double), or $\ge$3 (multiple) transits occurring while observations are being taken. We also investigate the effects of collaboration by performing the same calculations with combined observing times from two wide-f… ▽ More This paper investigates the effects of observing windows on detecting transiting planets by calculating the fraction of planets with a given period that have zero, one (single), two (double), or $\ge$3 (multiple) transits occurring while observations are being taken. We also investigate the effects of collaboration by performing the same calculations with combined observing times from two wide-field transit survey groups. For a representative field of the 2004 observing season, both XO and SuperWASP experienced an increase in single and double transit events by up to 20-40% for planets with periods 14 < P < 150 days when collaborating by sharing data. For the XO Project using its data alone, between 20-40% of planets with periods 14-150 days should have been observed at least once. For the SuperWASP Project, 50-90% of planets with periods between 14-150 days should have been observed at least once. If XO and SuperWASP combined their observations, 50-100% of planets with periods less than 20 days should be observed three or more times. We find that in general wide-field transit surveys have selected appropriate observing strategies to observe a significant fraction of transiting giant planets with semimajor axes larger than the Hot Jupiter regime. The actual number of intermediate-period transiting planets that are detected depends upon their true semimajor axis distribution and the signal-to-noise of the data. △ Less

Submitted 17 February, 2008; originally announced February 2008.

Comments: 14 pages, 12 figures, 4 tables, accepted to MNRAS

XO-3b: A Massive Planet in an Eccentric Orbit Transiting an F5V Star

Authors: Christopher M. Johns-Krull, Peter R. McCullough, Christopher J. Burke, Jeff A. Valenti, K. A. Janes, J. N. Heasley, L. Prato, R. Bissinger, M. Fleenor, C. N. Foote, E. Garcia-Melendo, B. L. Gary, P. J. Howell, F. Mallia, G. Masi, T. Vanmunster

Abstract: We report the discovery of a massive (Mpsini = 13.02 +/- 0.64 Mjup; total mass 13.25 +/- 0.64 Mjup), large (1.95 +/- 0.16 Rjup) planet in a transiting, eccentric orbit (e = 0.260 +/- 0.017) around a 10th magnitude F5V star in the constellation Camelopardalis. We designate the planet XO-3b, and the star XO-3, also known as GSC 03727-01064. The orbital period of XO-3b is 3.1915426 +/- 0.00014 days… ▽ More We report the discovery of a massive (Mpsini = 13.02 +/- 0.64 Mjup; total mass 13.25 +/- 0.64 Mjup), large (1.95 +/- 0.16 Rjup) planet in a transiting, eccentric orbit (e = 0.260 +/- 0.017) around a 10th magnitude F5V star in the constellation Camelopardalis. We designate the planet XO-3b, and the star XO-3, also known as GSC 03727-01064. The orbital period of XO-3b is 3.1915426 +/- 0.00014 days. XO-3 lacks a trigonometric distance; we estimate its distance to be 260 +/- 23 pc. The radius of XO-3 is 2.13 +/- 0.21 Rsun, its mass is 1.41 +/- 0.08 Msun, its vsini = 18.54 +/- 0.17 km/s, and its metallicity is [Fe/H] = -0.177 +/- 0.027. This system is unusual for a number of reasons. XO-3b is one of the most massive planets discovered around any star for which the orbital period is less than 10 days. The mass is near the deuterium burning limit of 13 Mjup, which is a proposed boundary between planets and brown dwarfs. Although Burrows et al. (2001) propose that formation in a disk or formation in the interstellar medium in a manner similar to stars is a more logical way to differentiate planets and brown dwarfs, our current observations are not adequate to address this distinction. XO-3b is also unusual in that its eccentricity is large given its relatively short orbital period. Both the planetary radius and the inclination are functions of the spectroscopically determined stellar radius. Analysis of the transit light curve of XO-3b suggests that the spectroscopically derived parameters may be over estimated. Though relatively noisy, the light curves favor a smaller radius in order to better match the steepness of the ingress and egress. The light curve fits imply a planetary radius of 1.25 +/- 0.15 Rjup, which would correspond to a mass of 12.03 +/- 0.46 Mjup. △ Less

Submitted 14 March, 2008; v1 submitted 27 December, 2007; originally announced December 2007.

Comments: 26 pages, 10 figures. Accepted by ApJ. Current version has several small corrections as a result of a bug in the fitting software

XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary

Authors: Christopher J. Burke, P. R. McCullough, Jeff A. Valenti, Christopher M. Johns-Krull, Kenneth A. Janes, J. N. Heasley, F. J. Summers, J. E. Stys, R. Bissinger, Michael L. Fleenor, Cindy N. Foote, Enrique Garcia-Melendo, Bruce L. Gary, P. J. Howell, F. Mallia, G. Masi, B. Taylor, T. Vanmunster

Abstract: We report on a V=11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a Rp=0.98+0.03/-0.01 Rjup, Mp=0.57+/-0.06 Mjup transiting extrasolar planet, XO-2b, with an orbital period of 2.615857+/-0.000005 days. XO-2 has high metallicity, [Fe/H]=0.45+/-0.02, high proper motion, mu_tot=157 mas/yr, and has a common proper motion stellar companion with 31" separation. The two stars are nearly identical… ▽ More We report on a V=11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a Rp=0.98+0.03/-0.01 Rjup, Mp=0.57+/-0.06 Mjup transiting extrasolar planet, XO-2b, with an orbital period of 2.615857+/-0.000005 days. XO-2 has high metallicity, [Fe/H]=0.45+/-0.02, high proper motion, mu_tot=157 mas/yr, and has a common proper motion stellar companion with 31" separation. The two stars are nearly identical twins, with very similar spectra and apparent magnitudes. Due to the high metallicity, these early K dwarf stars have a mass and radius close to solar, Ms=0.98+/-0.02 Msolar and Rs=0.97+0.02/-0.01 Rsolar. The high proper motion of XO-2 results from an eccentric orbit (Galactic pericenter, Rper<4 kpc) well confined to the Galactic disk (Zmax~100 pc). In addition, the phase space position of XO-2 is near the Hercules dynamical stream, which points to an origin of XO-2 in the metal-rich, inner Thin Disk and subsequent dynamical scattering into the solar neighborhood. We describe an efficient Markov Chain Monte Carlo algorithm for calculating the Bayesian posterior probability of the system parameters from a transit light curve. △ Less

Submitted 12 September, 2007; v1 submitted 1 May, 2007; originally announced May 2007.

Comments: 14 pages, 10 Figures, Accepted in ApJ. Negligible changes to XO-2 system properties. Removed Chi^2 light curve analysis section, and simplified MCMC light curve analysis discussion

The Life Cycle of an XO Planet and the Potential to Detect Transiting Planets of M Dwarfs

Authors: Peter R. McCullough, Christopher J. Burke

Abstract: We describe strategies and tactics for detecting transiting planets, as learned from the experience of the XO Project. A key component is the web-enabled collaboration with a longitudinally-distributed Extended Team of dedicated volunteers operating small-aperture telescopes near their homes. We also quantify the (small) potential to discover transiting planets of M dwarfs from existing data suc… ▽ More We describe strategies and tactics for detecting transiting planets, as learned from the experience of the XO Project. A key component is the web-enabled collaboration with a longitudinally-distributed Extended Team of dedicated volunteers operating small-aperture telescopes near their homes. We also quantify the (small) potential to discover transiting planets of M dwarfs from existing data such as that obtained by the XO Project. △ Less

Submitted 13 March, 2007; originally announced March 2007.

Comments: 8 pages, 2 figures. To appear in the ASP Conference Series: "Transiting Extrasolar Planets Workshop" MPIA Heidelberg Germany, 25-28 September 2006. Eds: Cristina Afonso, David Weldrake & Thomas Henning

Observations of Extrasolar Planets Enabled by a Return to the Moon

Authors: P. R. McCullough

Abstract: Ambitious studies of Earth-like extrasolar planets are outlined in the context of an exploration initiative for a return to the Earth's Moon. Two mechanism for linearly polarizing light reflected from Earth-like planets are discussed: 1) Rayleigh-scattering from a planet's clear atmosphere, and 2) specular reflection from a planet's ocean. Both have physically simple and predictable polarized ph… ▽ More Ambitious studies of Earth-like extrasolar planets are outlined in the context of an exploration initiative for a return to the Earth's Moon. Two mechanism for linearly polarizing light reflected from Earth-like planets are discussed: 1) Rayleigh-scattering from a planet's clear atmosphere, and 2) specular reflection from a planet's ocean. Both have physically simple and predictable polarized phase functions. The exoplanetary diurnal variation of the polarized light reflected from a ocean but not from a land surface has the potential to enable reconstruction of the continental boundaries on an Earth-like extrasolar planet. Digressions on the lunar exploration initiative also are presented. △ Less

Submitted 13 March, 2007; originally announced March 2007.

Comments: To be published in Astrophysics Enabled by the Return to the Moon, Ed. M. Livio (Cambridge: Cambridge University Press), 2007