Gilbert A. Esquerdo - Harvard-Smithsonian Center for Astrophysics

Gilbert A. Esquerdo
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Gilbert A. Esquerdo
Harvard-Smithsonian Center for Astrophysics
United States

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Pub Categories

Earth and Planetary Astrophysics (28)
Solar and Stellar Astrophysics (16)
Astrophysics (10)
Instrumentation and Methods for Astrophysics (1)
Cosmology and Nongalactic Astrophysics (1)

Publications Authored By Gilbert A. Esquerdo

M dwarf stars, which have masses less than 60 per cent that of the Sun, make up 75 per cent of the population of the stars in the Galaxy [1]. The atmospheres of orbiting Earth-sized planets are observationally accessible via transmission spectroscopy when the planets pass in front of these stars [2,3]. Statistical results suggest that the nearest transiting Earth-sized planet in the liquid-water, habitable zone of an M dwarf star is probably around 10. Read More

The determination of exoplanet properties and occurrence rates using Kepler data critically depends on our knowledge of the fundamental properties (such as temperature, radius and mass) of the observed stars. We present revised stellar properties for 197,096 Kepler targets observed between Quarters 1-17 (Q1-17), which were used for the final transiting planet search run by the Kepler Mission (Data Release 25, DR25). Similar to the Q1--16 catalog by Huber et al. Read More

We report the detection of stellar eclipses in the LP 661-13 system. We present the discovery and characterization of this system, including high resolution spectroscopic radial velocities and a photometric solution spanning two observing seasons. LP 661-13 is a low mass binary system with an orbital period of $4. Read More

We report the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting a mildly evolved host star. We identified the initial transit signal in the KELT-North survey data and established the planetary nature of the companion through precise follow-up photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging. Our preferred best-fit model indicates that the $V = 10. Read More

The Kepler mission has revealed a great diversity of planetary systems and architectures, but most of the planets discovered by Kepler orbit faint stars. Using new data from the K2 mission, we present the discovery of a five planet system transiting a bright (V = 8.9, K = 7. Read More

We report the discovery of Qatar-3b, Qatar-4b, and Qatar-5b, three new transiting planets identified by the Qatar Exoplanet Survey (QES). The three planets belong to the hot Jupiter family, with orbital periods of $P_{Q3b}$=2.50792 days, $P_{Q4b}$=1. Read More

We present Doppler tomographic analyses for the spectroscopic transits of KELT-7b and HAT-P-56b, two hot-Jupiters orbiting rapidly rotating F-dwarf host stars. These include analyses of archival TRES observations for KELT-7b, and a new TRES transit observation of HAT-P-56b. We report spin-orbit aligned geometries for KELT-7b (2. Read More

The Kepler Space Telescope is currently searching for planets transiting stars along the ecliptic plane as part of its extended K2 mission. We processed the publicly released data from the first year of K2 observations (Campaigns 0, 1, 2, and 3) and searched for periodic eclipse signals consistent with planetary transits. Out of 59,174 targets we searched, we detect 234 planetary candidates around 208 stars. Read More

We report the discovery of KELT-6b, a mildly-inflated Saturn-mass planet transiting a metal-poor host. The initial transit signal was identified in KELT-North survey data, and the planetary nature of the occulter was established using a combination of follow-up photometry, high-resolution imaging, high-resolution spectroscopy, and precise radial velocity measurements. The fiducial model from a global analysis including constraints from isochrones indicates that the V=10. Read More

Affiliations: 1Department of Physics and Astronomy, San Jose State University, 2SETI Institute/NASA Ames Research Center, 3NASA Ames Research Center, 4Bay Area Environmental Research Institute/NASA Ames Research Center, 5SETI Institute/NASA Ames Research Center, 6SETI Institute/NASA Ames Research Center, 7NASA Ames Research Center, 8SETI Institute/NASA Ames Research Center, 9SETI Institute/NASA Ames Research Center, 10Las Cumbres Observatory Global Telescope Network, 11Harvard-Smithsonian Center for Astrophysics, 12Department of Astronomy and Astrophysics, University of California, 13University of Florida, 14Department of Astronomy and Astrophysics, University of California, 15Center for Exoplanets and Habitable Worlds, The Pennsylvania State University, 16University of California, Berkeley, 17Harvard-Smithsonian Center for Astrophysics, 18University of California, Berkeley, 19Harvard-Smithsonian Center for Astrophysics, 20Harvard-Smithsonian Center for Astrophysics, 21Las Cumbres Observatory Global Telescope Network, 22NASA Ames Research Center, 23NASA Exoplanet Science Institute/Caltech, 24Jet Propulsion Laboratory/California Institute of Technology, 25NASA Ames Research Center, 26SETI Institute/NASA Ames Research Center, 27NASA Ames Research Center, 28NASA Ames Research Center, 29NASA Ames Research Center, 30University of California, Berkeley, 31Carnegie Institution of Washington, 32Niels Bohr Institute, University of Copenhagen, 33Harvard-Smithsonian Center for Astrophysics, 34Aarhus University, 35Jet Propulsion Laboratory/California Institute of Technology, 36McDonald Observatory, The University of Texas, 37Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 38SETI Institute, 39Harvard-Smithsonian Center for Astrophysics, 40National Optical Astronomy Observatory, 41Harvard-Smithsonian Center for Astrophysics, 42Harvard-Smithsonian Center for Astrophysics, 43Orbital Sciences Corporation/NASA Ames Research Center, 44Lawrence Hall of Science, 45Orbital Sciences Corporation/NASA Ames Research Center, 46Harvard-Smithsonian Center for Astrophysics, 47University of California, Berkeley, 48NASA Ames Research Center, 49Orbital Sciences Corporation/NASA Ames Research Center, 50SETI Institute/NASA Ames Research Center, 51Aarhus University, 52Orbital Sciences Corporation/NASA Ames Research Center, 53SETI Institute/NASA Ames Research Center, 54Centre for Astrophysics, University of Hertfordshire, 55Orbital Sciences Corporation/NASA Ames Research Center, 56Villanova University, 57SETI Institute/NASA Ames Research Center, 58Orbital Sciences Corporation/NASA Ames Research Center, 59Harvard-Smithsonian Center for Astrophysics, 60SETI Institute/NASA Ames Research Center, 61SETI Institute/NASA Ames Research Center, 62Fermilab Center for Particle Astrophysics, 63Bay Area Environmental Research Institute/NASA Ames Research Center, 64SETI Institute/NASA Ames Research Center, 65SETI Institute, 66SETI Institute/NASA Ames Research Center, 67Harvard-Smithsonian Center for Astrophysics, 68SETI Institute/NASA Ames Research Center, 69Orbital Sciences Corporation/NASA Ames Research Center, 70SETI Institute/NASA Ames Research Center, 71Department of Astrophysical Sciences, Princeton University, 72San Diego State University

New transiting planet candidates are identified in sixteen months (May 2009 - September 2010) of data from the Kepler spacecraft. Nearly five thousand periodic transit-like signals are vetted against astrophysical and instrumental false positives yielding 1,091 viable new planet candidates, bringing the total count up to over 2,300. Improved vetting metrics are employed, contributing to higher catalog reliability. Read More

Affiliations: 1Las Cumbres Observatory Global Telescope, 2Harvard_Smithsonian Center for Astrophysics, 3National Optical Astronomy Observatories, 4Harvard_Smithsonian Center for Astrophysics

We describe the photometric calibration and stellar classification methods used to produce the Kepler Input Catalog (KIC). The KIC is a catalog containing photometric and physical data for sources in the Kepler Mission field of view; it is used by the mission to select optimal targets. We derived atmospheric extinction corrections from hourly observations of secondary standard fields within the Kepler field of view. Read More

We report the discovery of an eclipsing companion to NLTT 41135, a nearby M5 dwarf that was already known to have a wider, slightly more massive common proper motion companion, NLTT 41136, at 2.4 arcsec separation. Analysis of combined-light and radial velocity curves of the system indicates that NLTT 41135B is a 31-34 +/- 3 MJup brown dwarf (where the range depends on the unknown metallicity of the host star) on a circular orbit. Read More

We present new spectroscopic and photometric observations of the transiting exoplanetary system WASP-3. Spectra obtained during two separate transits exhibit the Rossiter-McLaughlin (RM) effect and allow us to estimate the sky-projected angle between the planetary orbital axis and the stellar rotation axis, lambda = 3.3^{+2. Read More

Affiliations: 1Harvard-Smithsonian Center for Astrophysics, 2Harvard-Smithsonian Center for Astrophysics, 3Harvard-Smithsonian Center for Astrophysics, 4Harvard-Smithsonian Center for Astrophysics, 5Department of Physics and Astronomy, San Francisco State University, 6Institute for Astronomy, University of Hawaii, 7Center of Excellence in Information Systems, Tennessee State University, 8Department of Terrestrial Magnetism, Carnegie Institute of Washington, 9Department of Astronomy, University of California, Berkeley, 10Department of Astronomy, University of California, Berkeley, 11Harvard-Smithsonian Center for Astrophysics, 12Harvard-Smithsonian Center for Astrophysics, 13Harvard-Smithsonian Center for Astrophysics

We present refined parameters for the extrasolar planetary system HAT-P-2 (also known as HD 147506), based on new radial velocity and photometric data. HAT-P-2b is a transiting extrasolar planet that exhibits an eccentric orbit. We present a detailed analysis of the planetary and stellar parameters, yielding consistent results for the mass and radius of the star, better constraints on the orbital eccentricity, and refined planetary parameters. Read More

We have derived masses and radii for both components in five short-period single-lined eclipsing binary stars discovered by the TrES wide-angle photometric survey for transiting planets. All these systems consist of a visible F-star primary and an unseen M-star secondary (M_A > 0.8 M_sun, M_B < 0. Read More

Affiliations: 1Harvard-Smithsonian Center for Astrophysics, 2Harvard-Smithsonian Center for Astrophysics, 3Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 4Harvard-Smithsonian Center for Astrophysics, 5Wise Observatory, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 6Wise Observatory, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, 7Harvard-Smithsonian Center for Astrophysics, 8Planetary Science Institute

We present photometry of six transits of the exoplanet XO-2b. By combining the light-curve analysis with theoretical isochrones to determine the stellar properties, we find the planetary radius to be 0.996 +0. Read More

Affiliations: 1CfA, 2CfA, 3CfA, 4CfA, 5CfA, 6Konkoly Observatory, 7CfA, 8UC Berkeley, 9SFSU, 10Carnegie, 11ELTE, 12CfA, 13CfA, 14UC Santa Cruz, 15CfA, 16CfA, 17Hungarian Astronomical Association, 18Hungarian Astronomical Association, 19Hungarian Astronomical Association
Category: Astrophysics

We report the identification of 32 transiting-planet candidates in HATNet field G205. We describe the procedures that we have used to follow up these candidates with spectroscopic and photometric observations, and we present a status report on our interpretation of the 28 candidates for which we have follow-up observations. Eight are eclipsing binaries with orbital solutions whose periods are consistent with their photometric ephemerides; two of these spectroscopic orbits are singled-lined and six are double-lined. Read More

This paper presents multi-band photometric follow-up observations of the Neptune-mass transiting planet GJ 436b, consisting of 5 new ground-based transit light curves obtained in May 2007. Together with one already published light curve we have at hand a total of 6 light curves, spanning 29 days. The analysis of the data yields an orbital period P = 2. Read More

We report the discovery of TrES-4, a hot Jupiter that transits the star GSC 02620-00648 every 3.55 days. From high-resolution spectroscopy of the star we estimate a stellar effective temperature of Teff = 6100 +/- 150 K, and from high-precision z and B photometry of the transit we constrain the ratio of the semi-major axis and the stellar radius to be a/R = 6. Read More

We present precise z-band photometric time series spanning times of transit of the two exoplanets recently discovered by the SuperWASP collaboration. We find planetary radii of 1.44 +/- 0. Read More

We present RIz photometry of four consecutive transits of the newly discovered exoplanet XO-1b. We improve upon the estimates of the transit parameters, finding the planetary radius to be R_P = 1.184 +0. Read More

Ground-based wide-field surveys for nearby transiting gas giants are yielding far fewer true planets than astrophysical false positives, of which some are difficult to reject. Recent experience has highlighted the need for careful analysis to eliminate astronomical systems where light from a faint eclipsing binary is blended with that from a bright star. During the course of the Trans-atlantic Exoplanet Survey, we identified a system presenting a transit-like periodic signal. Read More

We report g, V, and r photometric time series of HD 149026 spanning predicted times of transit of the Saturn-mass planetary companion, which was recently discovered by Sato and collaborators. We present a joint analysis of our observations and the previously reported photometry and radial velocities of the central star. We refine the estimate of the transit ephemeris to Tc [HJD] = 2453527. Read More