This is a list of my refereed publications
Showing 1–37 of 37 results for author: Gregorio, J
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arXiv:2507.13588 [pdf, ps, other]
Updated Masses for the Gas Giants in the Eight-Planet Kepler-90 System Via Transit-Timing Variation and Radial Velocity Observations
Abstract: The eight-planet Kepler-90 system exhibits the greatest multiplicity of planets found to date. All eight planets are transiting and were discovered in photometry from the NASA Kepler primary mission. The two outermost planets, g (
= 211 d) and h (
= 332 d) exhibit significant transit-timing variations (TTVs), but were only observed 6 and 3 times respectively by Kepler. These TTVs allow f… ▽ MoreSubmitted 17 July, 2025; originally announced July 2025.
Comments: 20 pages, 13 figures, 6 tables, accepted for publication in AJ
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Wide Binary Orbits are Preferentially Aligned with the Orbits of Small Planets, but Probably Not Hot Jupiters
Abstract: Studying the relative orientations of the orbits of exoplanets and wide-orbiting binary companions (semimajor axis greater than 100 AU) can shed light on how planets form and evolve in binary systems. Previous observations by multiple groups discovered a possible alignment between the orbits of visual binaries and the exoplanets that reside in them. In this study, using data from \textit{Gaia} DR3… ▽ More
Submitted 16 May, 2024; originally announced May 2024.
Comments: 16 pages, 10 figures, submitted to AJ. Email corresponding author for data files
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The TESS-Keck Survey XXI: 13 New Planets and Homogeneous Properties for 21 Subgiant Systems
Abstract: We present a dedicated transit and radial velocity survey of planets orbiting subgiant stars observed by the TESS Mission. Using
nights on Keck/HIRES, we confirm and characterize 
new transiting planets — 
, 
(
), , , , , 
, ,… ▽ MoreSubmitted 12 February, 2024; originally announced February 2024.
Comments: 22 pages, 9 figures, 9 tables
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TOI-1199 b and TOI-1273 b: Two new transiting hot Saturns detected and characterized with SOPHIE and TESS
Abstract: We report the characterization of two planet candidates detected by the Transiting Exoplanet Survey Satellite (TESS), TOI-1199 b and TOI-1273 b, with periods of 3.7 and 4.6 days, respectively. Follow-up observations for both targets, which include several ground-based light curves, confirmed the transit events. High-precision radial velocities from the SOPHIE spectrograph revealed signals at the e… ▽ More
Submitted 29 March, 2024; v1 submitted 12 February, 2024; originally announced February 2024.
Comments: Accepted for publication in A&A. 20 pages, 7 tables, and 15 figures
Journal ref: A&A, 684, A6 (2024)
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Confirmation of a Sub-Saturn-size transiting exoplanet orbiting a G dwarf: TOI-1194 b and a very low mass companion star: TOI-1251 B from TESS
Abstract: We report the confirmation of a sub-Saturn-size exoplanet, TOI-1194 b with a mass about
, and a very low mass companion star with a mass of about 
, TOI-1251 B. Exoplanet candidates provided by the Transiting Exoplanet Survey Satellite (TESS) are suitable for further follow-up observations by ground-based telescopes with small and medium apertures.… ▽ MoreSubmitted 20 October, 2023; v1 submitted 19 October, 2023; originally announced October 2023.
Comments: 28 pages, 8 figures, Accepted by RAA on Oct. 18th, 2023
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Identification of the Top TESS Objects of Interest for Atmospheric Characterization of Transiting Exoplanets with JWST
Abstract: JWST has ushered in an era of unprecedented ability to characterize exoplanetary atmospheres. While there are over 5,000 confirmed planets, more than 4,000 TESS planet candidates are still unconfirmed and many of the best planets for atmospheric characterization may remain to be identified. We present a sample of TESS planets and planet candidates that we identify as “best-in-class” for transmissi… ▽ More
Submitted 18 August, 2023; originally announced August 2023.
Comments: Submitted to AJ. Machine-readable versions of Tables 2 and 3 are included. 40 pages, 7 figures, 3 tables
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TIC~257060897b: an inflated, low-density, hot-Jupiter transiting a rapidly evolving subgiant star
Abstract: We report the discovery of a new transiting exoplanet orbiting the star TIC~257060897 and detected using {\it TESS} full frame images. We acquired HARPS-N time-series spectroscopic data, and ground-based photometric follow-up observations from which we confirm the planetary nature of the transiting body. For the host star we determined: T
=(612857) K, log~g=(4.20.1) and [Fe/H]=… ▽ MoreSubmitted 1 October, 2021; originally announced October 2021.
Comments: Accepted for publication in MNRAS
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KELT-25b and KELT-26b: A Hot Jupiter and a Substellar Companion Transiting Young A-stars Observed by TESS
Abstract: We present the discoveries of KELT-25b (TIC 65412605, TOI-626.01) and KELT-26b (TIC 160708862, TOI-1337.01), two transiting companions orbiting relatively bright, early A-stars. The transit signals were initially detected by the KELT survey, and subsequently confirmed by \textit{TESS} photometry. KELT-25b is on a 4.40-day orbit around the V = 9.66 star CD-24 5016 (… ▽ More
Submitted 2 December, 2019; originally announced December 2019.
Comments: 24 pages, 18 figures, 8 tables
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KELT-24b: A 5M
Planet on a 5.6 day Well-Aligned Orbit around the Young V=8.3 F-star HD 93148Abstract: We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V=8.3 mag, K=7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a
=
K, a mass of 
= 
, radius of 
= , and an age of 
Gyr. Its planetary companion (KELT-… ▽ MoreSubmitted 3 September, 2019; v1 submitted 7 June, 2019; originally announced June 2019.
Comments: 18 pages, 10 Figures, 6 Tables, Accepted to the Astronomical Journal
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KELT-23Ab: A Hot Jupiter Transiting a Near-Solar Twin Close to the TESS and JWST Continuous Viewing Zones
Abstract: We announce the discovery of KELT-23Ab, a hot Jupiter transiting the relatively bright (
) star BD+66 911 (TYC 4187-996-1), and characterize the system using follow-up photometry and spectroscopy. A global fit to the system yields host-star properties of 
, , , 
, lo… ▽ MoreSubmitted 28 May, 2019; v1 submitted 28 February, 2019; originally announced March 2019.
Comments: 17 pages, 10 figures, Accepted for publication in AJ
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KELT-22Ab: A Massive Hot Jupiter Transiting a Near Solar Twin
Abstract: We present the discovery of KELT-22Ab, a hot Jupiter from the KELT-South survey. KELT-22Ab transits the moderately bright (
) Sun-like G2V star TYC 7518-468-1. The planet has an orbital period of days, a radius of 
, and a relatively large mass of . The star has… ▽ MoreSubmitted 20 March, 2018; originally announced March 2018.
Comments: 14 pages, 13 figures, 5 tables
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The KELT Follow-Up Network and Transit False Positive Catalog: Pre-vetted False Positives for TESS
Abstract: The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey for transiting planets orbiting bright stars for over ten years. The KELT images have a pixel scale of ~23″/pixel—very similar to that of NASA’s Transiting Exoplanet Survey Satellite (TESS)—as well as a large point spread function, and the KELT reduction pipeline uses a weighted photometric apertu… ▽ More
Submitted 19 September, 2018; v1 submitted 5 March, 2018; originally announced March 2018.
Comments: Accepted for publication in AJ, 21 pages, 12 figures, 7 tables
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The First Post-Kepler Brightness Dips of KIC 8462852
Abstract: We present a photometric detection of the first brightness dips of the unique variable star KIC 8462852 since the end of the Kepler space mission in 2013 May. Our regular photometric surveillance started in October 2015, and a sequence of dipping began in 2017 May continuing on through the end of 2017, when the star was no longer visible from Earth. We distinguish four main 1-2.5% dips, named “Els… ▽ More
Submitted 2 January, 2018; originally announced January 2018.
Comments: 19 pages, 8 figures, accepted for publication in ApJL
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KELT-21b: A Hot Jupiter Transiting the Rapidly-Rotating Metal-Poor Late-A Primary of a Likely Hierarchical Triple System
Abstract: We present the discovery of KELT-21b, a hot Jupiter transiting the
A8V star HD 332124. The planet has an orbital period of days and a radius of 
. We set an upper limit on the planetary mass of 
at 
confidence. We confirmed the planetary nature of the transiting companion using this mass limit and Doppler tomograp… ▽ MoreSubmitted 17 January, 2018; v1 submitted 8 December, 2017; originally announced December 2017.
Comments: Accepted for publication in AJ. Updated to match accepted version. 25 pages, 14 figures
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KELT-19Ab: A P~4.6 Day Hot Jupiter Transiting a Likely Am Star with a Distant Stellar Companion
Abstract: We present the discovery of the giant planet KELT-19Ab, which transits the moderately bright
A8V star TYC 764-1494-1 with an orbital period of 4.61 days. We confirm the planetary nature of the companion via a combination of radial velocities, which limit the mass to 
, and a clear Doppler tomography signal, which indicates a retrograde projected s… ▽ MoreSubmitted 22 December, 2017; v1 submitted 20 September, 2017; originally announced September 2017.
Comments: Published in The Astronomical Journal. 18 pages, 14 figures, 6 tables
Journal ref: Robert J. Siverd et al. 2018 AJ 155 35
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KELT-20b: A giant planet with a period of P~ 3.5 days transiting the V~ 7.6 early A star HD 185603
Abstract: We report the discovery of KELT-20b, a hot Jupiter transiting a V~7.6 early A star with an orbital period of P~3.47 days. We identified the initial transit signal in KELT-North survey data. Archival and follow-up photometry, the Gaia parallax, radial velocities, Doppler tomography, and adaptive optics imaging were used to confirm the planetary nature of the companion and characterize the system. F… ▽ More
Submitted 5 July, 2017; originally announced July 2017.
Comments: 14 pages, 14 figures, 6 tables, submitted to AAS journals
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A giant planet undergoing extreme ultraviolet irradiation by its hot massive-star host
Abstract: The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extra-solar planets now known, only four giant planets have been found that transit hot, A-type stars (temperatures of 7300-10,000K), and none are known to transit even hotter B-type stars. WASP-33 is an A-type star with a temperature of ~7430K, which… ▽ More
Submitted 20 June, 2017; originally announced June 2017.
Comments: 39 pages, 3 figures, 1 table, 3 extended data figures, 3 extended data tables. Published in Nature on 22 June 2017
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WASP-167b/KELT-13b: Joint discovery of a hot Jupiter transiting a rapidly-rotating F1V star
Abstract: We report the joint WASP/KELT discovery of WASP-167b/KELT-13b, a transiting hot Jupiter with a 2.02-d orbit around a
= 10.5, F1V star with [Fe/H] = 0.1 0.1. The 1.5 R
planet was confirmed by Doppler tomography of the stellar line profiles during transit. We place a limit of 8 M on its mass. The planet is in a retrograde orbit with a sky-projected spin-orbit an… ▽ MoreSubmitted 7 July, 2017; v1 submitted 25 April, 2017; originally announced April 2017.
Comments: 11 pages, 8 figures, accepted by MNRAS
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KELT-18b: Puffy Planet, Hot Host, Probably Perturbed
Abstract: We report the discovery of KELT-18b, a transiting hot Jupiter in a 2.87d orbit around the bright (V=10.1), hot, F4V star BD+60 1538 (TYC 3865-1173-1). We present follow-up photometry, spectroscopy, and adaptive optics imaging that allow a detailed characterization of the system. Our preferred model fits yield a host stellar temperature of 6670+/-120 K and a mass of 1.524+/-0.069 Msun, situating it… ▽ More
Submitted 10 April, 2017; v1 submitted 6 February, 2017; originally announced February 2017.
Comments: 16 pages, 13 figures, 6 tables, accepted to AJ
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KELT-12b: A
Day, Highly Inflated Hot Jupiter Transiting a Mildly Evolved Hot StarAbstract: 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 prefer… ▽ More
Submitted 2 September, 2016; v1 submitted 16 August, 2016; originally announced August 2016.
Comments: 16 pages, 14 figures, 6 tables. Submitted to AAS Journals
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arXiv:1608.00618 [pdf, ps, other]
KELT-16b: A highly irradiated, ultra-short period hot Jupiter nearing tidal disruption
Abstract: We announce the discovery of KELT-16b, a highly irradiated, ultra-short period hot Jupiter transiting the relatively bright (
) star TYC 2688-1839-1. A global analysis of the system shows KELT-16 to be an F7V star with K, 
, [Fe/H] = -0.002, , and… ▽ MoreSubmitted 31 January, 2017; v1 submitted 1 August, 2016; originally announced August 2016.
Comments: 16 pages, 18 Figures, 7 Tables, Accepted for publication in AJ
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arXiv:1607.03512 [pdf, ps, other]
KELT-17b: A hot-Jupiter transiting an A-star in a misaligned orbit detected with Doppler tomography
Abstract: We present the discovery of a hot-Jupiter transiting the V=9.23 mag main-sequence A-star KELT-17 (BD+14 1881). KELT-17b is a 1.31 -0.29/+0.28 Mj, 1.525 -0.060/+0.065 Rj hot-Jupiter in a 3.08 day period orbit misaligned at -115.9 +/- 4.1 deg to the rotation axis of the star. The planet is confirmed via both the detection of the radial velocity orbit, and the Doppler tomographic detection of the sha… ▽ More
Submitted 2 September, 2016; v1 submitted 12 July, 2016; originally announced July 2016.
Comments: 15 pages, 9 figures, accepted for publication in AJ
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The SOPHIE search for northern extrasolar planets. X. Detection and characterization of giant planets by the dozen
Abstract: We present new radial velocity measurements of eight stars secured with the spectrograph SOPHIE at the 193-cm telescope of the Haute-Provence Observatory allowing the detection and characterization of new giant extrasolar planets. The host stars are dwarfs of spectral types between F5 and K0 and magnitudes between 6.7 and 9.6; the planets have minimum masses M_p sin i between 0.4 to 3.8 M_Jup and… ▽ More
Submitted 15 February, 2016; originally announced February 2016.
Comments: 20 pages, 19 figures, 5 tables, accepted for publication in A&A
Journal ref: A&A 588, A145 (2016)
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EPIC211089792 b: an aligned and inflated hot jupiter in a young visual binary
Abstract: In the present paper we report the discovery of a new hot Jupiter, EPIC211089792 b, first detected by the Super-WASP observatory and then by the K2 space mission during its campaign 4. The planet has a period of 3.25d, a mass of 0.73 +/- 0.04 Mjup, and a radius of 1.19 +/- 0.02 Rjup. The host star is a relatively bright (V=12.5) G7 dwarf with a nearby K5V companion. Based on stellar rotation and t… ▽ More
Submitted 28 January, 2016; originally announced January 2016.
Comments: Submitted to ApJ
Journal ref: 2016, ApJ, 825, 55
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Kepler-1647b: the largest and longest-period Kepler transiting circumbinary planet
Abstract: We report the discovery of a new Kepler transiting circumbinary planet (CBP). This latest addition to the still-small family of CBPs defies the current trend of known short-period planets orbiting near the stability limit of binary stars. Unlike the previous discoveries, the planet revolving around the eclipsing binary system Kepler-1647 has a very long orbital period (~1100 days) and was at conju… ▽ More
Submitted 19 May, 2016; v1 submitted 1 December, 2015; originally announced December 2015.
Comments: 61 pages, 21 figures
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arXiv:1510.00015 [pdf, ps, other]
KELT-4Ab: An inflated Hot Jupiter transiting the bright (V~10) component of a hierarchical triple
Abstract: We report the discovery of KELT-4Ab, an inflated, transiting Hot Jupiter orbiting the brightest component of a hierarchical triple stellar system. The host star is an F star with
K, , 
, , and… ▽ MoreSubmitted 30 September, 2015; originally announced October 2015.
Comments: 16 pages, 14 figures. Submitted to AJ
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The Physical Characterization of the Potentially-Hazardous Asteroid 2004 BL86: A Fragment of a Differentiated Asteroid
Abstract: The physical characterization of potentially hazardous asteroids (PHAs) is important for impact hazard assessment and evaluating mitigation options. Close flybys of PHAs provide an opportunity to study their surface photometric and spectral properties that enable identification of their source regions in the main asteroid belt. We observed PHA (357439) 2004 BL86 during a close flyby of the Earth a… ▽ More
Submitted 23 September, 2015; originally announced September 2015.
Comments: 27 pages, 8 figures, 4 tables. Accepted for publication in APJ
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KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra
Abstract: We announce the discovery of a highly inflated transiting hot Jupiter discovered by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with
K, , 
, an inferred mass M… ▽ MoreSubmitted 26 September, 2015; v1 submitted 25 May, 2015; originally announced May 2015.
Comments: Submitted to ApJ, feedback is welcome
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arXiv:1501.05565 [pdf, ps, other]
KELT-7b: A hot Jupiter transiting a bright V=8.54 rapidly rotating F-star
Abstract: We report the discovery of KELT-7b, a transiting hot Jupiter with a mass of
MJ, radius of RJ, and an orbital period of days. The bright host star (HD33643; KELT-7) is an F-star with , Teff K, [Fe/H] , and . It has a mass of Msun… ▽ MoreSubmitted 19 May, 2015; v1 submitted 22 January, 2015; originally announced January 2015.
Comments: Accepted to The Astronomical Journal
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SOPHIE velocimetry of Kepler transit candidates XII. KOI-1257 b: a highly eccentric three-month period transiting exoplanet
Abstract: In this paper we report a new transiting warm giant planet: KOI-1257 b. It was first detected in photometry as a planet-candidate by the
space telescope and then validated thanks to a radial velocity follow-up with the SOPHIE spectrograph. It orbits its host star with a period of 86.647661 d 3 s and a high eccentricity of 0.772 0.045. The planet transits the main star of… ▽ MoreSubmitted 21 August, 2014; v1 submitted 24 June, 2014; originally announced June 2014.
Comments: 39 pages, 17 figures, accepted for publication in Astronomy & Astrophysics
Journal ref: A&A 571, A37 (2014)
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The SOPHIE search for northern extrasolar planets: VI. Three new hot Jupiters in multi-planet extrasolar systems
Abstract: We present high-precision radial-velocity measurements of three solar-type stars: HD 13908, HD 159243, and HIP 91258. The observations were made with the SOPHIE spectrograph at the 1.93-m telescope of Observatoire de Haute-Provence (France). They show that these three bright stars host exoplanetary systems composed of at least two companions. HD 13908 b is a planet with a minimum mass of 0.865+-0.… ▽ More
Submitted 20 November, 2013; originally announced November 2013.
Comments: accepted in A&A
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arXiv:1308.2296 [pdf, ps, other]
KELT-6b: A P~7.9 d Hot Saturn Transiting a Metal-Poor Star with a Long-Period Companion
Abstract: 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 glo… ▽ More
Submitted 16 January, 2014; v1 submitted 10 August, 2013; originally announced August 2013.
Comments: Published in AJ, 17 pages, 15 figures, 6 tables
Journal ref: Collins, K. A., Eastman, J. D., Beatty, T. G. et al. 2014, AJ, 147, 39
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arXiv:1211.0218 [pdf, ps, other]
A new analysis of the WASP-3 system: no evidence for an additional companion
Abstract: In this work we investigate the problem concerning the presence of additional bodies gravitationally bounded with the WASP-3 system. We present eight new transits of this planet and analyse all the photometric and radial velocity data published so far. We did not observe significant periodicities in the Fourier spectrum of the observed minus calculated (O-C) transit timing and radial velocity diag… ▽ More
Submitted 1 November, 2012; originally announced November 2012.
Comments: MNRAS accepted (14/08/2012)
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arXiv:1111.5432 [pdf, ps, other]
Refined physical properties of the HAT-P-13 planetary system
Abstract: We present photometry of four transits of the planetary system HAT-P-13, obtained using defocussed telescopes. We analyse these, plus nine datasets from the literature, in order to determine the physical properties of the system. The mass and radius of the star are M_A = 1.320 +/- 0.048 +/- 0.039 Msun and R_A = 1.756 +/- 0.043 +/- 0.017 Rsun (statistical and systematic errorbars). We find the equi… ▽ More
Submitted 23 November, 2011; originally announced November 2011.
Comments: Accepted for publication in MNRAS. 8 pages, 5 tables, 3 figures. The results have been included in the TEPCat catalogue of transiting planets at http://www.astro.keele.ac.uk/~jkt/tepcat/
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arXiv:1004.0790 [pdf, ps, other]
Observation of the full 12-hour-long transit of the exoplanet HD80606b. Warm-Spitzer photometry and SOPHIE spectroscopy
Abstract: We present new observations of a transit of the 111-day-period exoplanet HD80606b. Using the Spitzer Space Telescope and its IRAC camera on the post-cryogenic mission, we performed a 19-hour-long photometric observation of HD80606 that covers the full transit of 13-14 January 2010. We complement this photometric data by new spectroscopic observations that we simultaneously performed with SOPHIE at… ▽ More
Submitted 6 April, 2010; originally announced April 2010.
Comments: 14 pages, 9 figures, 2 tables, accepted for publication in A&A
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arXiv:0805.2921 [pdf, ps, other]
XO-4b: An Extrasolar Planet Transiting an F5V Star
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
Submitted 19 May, 2008; originally announced May 2008.
Comments: 27 pages, 7 figures, submitted to ApJ
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arXiv:0805.2399 [pdf, ps, other]
XO-5b: A Transiting Jupiter-sized Planet With A Four Day Period
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
Submitted 15 May, 2008; originally announced May 2008.
Comments: 10 pages, 9 Figures, Submitted to ApJ
Journal ref: Astrophys.J.686:1331-1340,2008
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