William D. Cochran
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View article: <i>Searching for GEMS</i> : TOI-5349 b is a Saturn-like Planet Orbiting a Metal-rich Early M Dwarf
<i>Searching for GEMS</i> : TOI-5349 b is a Saturn-like Planet Orbiting a Metal-rich Early M Dwarf Open
We report the confirmation and analysis of TOI-5349 b, a transiting, warm, Saturn-like planet orbiting an early M dwarf with a period of ∼3.3 days, which we confirmed as part of the Searching for GEMS survey. TOI-5349 b was initially ident…
View article: Discovery of a Nearby Habitable Zone Super-Earth Candidate Amenable to Direct Imaging
Discovery of a Nearby Habitable Zone Super-Earth Candidate Amenable to Direct Imaging Open
We present the discovery of GJ 251 c, a candidate super-Earth orbiting in the habitable zone (HZ) of its M dwarf host star. Using high-precision Habitable-zone Planet Finder and NEID RVs, in conjunction with archival RVs from the Keck I Hi…
View article: Searching for GEMS: TOI-5916 b & TOI-6158 b are two Saturn-density planets orbiting M2 dwarfs
Searching for GEMS: TOI-5916 b & TOI-6158 b are two Saturn-density planets orbiting M2 dwarfs Open
We confirm the planetary nature of (1) TOI-5916 b and (2) TOI-6158 b, two Exoplanets Transiting M-dwarf Stars (GEMS), both discovered by the Transiting Exoplanet Survey Satellite (TESS). Both systems were confirmed with ground-based photom…
View article: A four-planet system orbiting the old thick disk star TOI-1203
A four-planet system orbiting the old thick disk star TOI-1203 Open
TOI-1203 is a bright (V,=,8.6) G3,V star known to host a transiting warm sub-Neptune on a 25.5-day orbit. Here we report on an intensive high-precision radial velocity and photometric follow-up campaign carried out with the spectrograph an…
View article: A four-planet system orbiting the old thick disk star TOI-1203
A four-planet system orbiting the old thick disk star TOI-1203 Open
TOI-1203 is a bright (V=8.6) G3 V star known to host a transiting warm sub-Neptune on a 25.5 d orbit. Here we report on an intensive high-precision radial velocity and photometric follow-up campaign carried out with the HARPS spectrograph …
View article: Searching for GEMS: The Occurrence of Giant Planets orbiting M-dwarfs within 100 pc
Searching for GEMS: The Occurrence of Giant Planets orbiting M-dwarfs within 100 pc Open
We present results from a systematic search for transiting short-period Giant Exoplanets around M-dwarf Stars (GEMS; $P < 10$ days, $R_p \gtrsim 8~R_\oplus$) within a distance-limited 100 pc sample of $149,316$ M-dwarfs using TESS-Gaia Lig…
View article: HET/HPF observations of Helium in warm, hot, and ultra-hot Jupiters
HET/HPF observations of Helium in warm, hot, and ultra-hot Jupiters Open
The near-infrared helium triplet line is a powerful tool for studying atmospheric escape processes of close-in exoplanets, especially irradiated gas giants. Line profile fitting provides direct insight into the mechanisms driving atmospher…
View article: Searching for GEMS: TOI-7149 b, an Inflated Giant Planet Causing a 12% Transit of a Fully Convective M-dwarf
Searching for GEMS: TOI-7149 b, an Inflated Giant Planet Causing a 12% Transit of a Fully Convective M-dwarf Open
We describe the discovery and characterization of TOI-7149 b, a 0.705 ± 0.075 M J , 1.18 ± 0.045 R J gas giant on a ∼2.65 days period orbit transiting an M4V star with a mass of 0.344 ± 0.030 M ⊙ and an effective temperature of 3363 ± 59 K…
View article: The Epoch of Giant Planet Migration Planet Search Program. III. The Occurrence Rate of Young Giant Planets inside the Water Ice Line<sup>*</sup>
The Epoch of Giant Planet Migration Planet Search Program. III. The Occurrence Rate of Young Giant Planets inside the Water Ice Line<sup>*</sup> Open
We present statistical results from the Epoch of Giant Planet Migration RV planet search program. This survey was designed to measure the occurrence rate of giant planets interior to the water ice line of young Sun-like stars, compare this…
View article: The First Planets
The First Planets Open
Both observations and theory indicate that there is a lower heavy element abundance threshold for planet formation at around 0.1 of solar ([Fe/H] of ~-1.0). The known planet-host stars in this low metallicity range are overwhelmingly membe…
View article: The Epoch of Giant Planet Migration Planet Search Program. III. The Occurrence Rate of Young Giant Planets Inside the Water Ice Line
The Epoch of Giant Planet Migration Planet Search Program. III. The Occurrence Rate of Young Giant Planets Inside the Water Ice Line Open
We present statistical results from the Epoch of Giant Planet Migration RV planet search program. This survey was designed to measure the occurrence rate of giant planets interior to the water ice line of young Sun-like stars, compare this…
View article: Searching for GEMS: Two Super-Jupiters Around M Dwarfs that May have Formed via Gravitational Instability
Searching for GEMS: Two Super-Jupiters Around M Dwarfs that May have Formed via Gravitational Instability Open
We present the discovery of TOI-6303b and TOI-6330b, two massive transiting super-Jupiters orbiting a M0 and a M2 dwarf star, respectively, as part of the Searching for Giant Exoplanets around M-dwarf Stars (GEMS) survey. These were detect…
View article: Planet Masses, Radii, and Orbits from NASA’s K2 Mission
Planet Masses, Radii, and Orbits from NASA’s K2 Mission Open
We report the masses, sizes, and orbital properties of 86 planets orbiting 55 stars observed by NASA’s K2 Mission with follow-up Doppler measurements by the HIRES spectrometer at the W. M. Keck Observatory and the Automated Planet Finder a…
View article: Searching for GEMS: Confirmation of TOI-5573b, a Cool, Saturn-like Planet Orbiting An M-dwarf
Searching for GEMS: Confirmation of TOI-5573b, a Cool, Saturn-like Planet Orbiting An M-dwarf Open
We present the confirmation of TOI-5573b, a Saturn-sized exoplanet on an 8.79-day orbit around an early M-dwarf (3790 K, 0.59 R$\odot$, 0.61 M$\odot$, 12.30 J mag). TOI-5573b has a mass of $112^{+18}_{-19}$ M$\oplus$ (0.35$\pm$0.06 M$\math…
View article: Searching for GEMS: Discovery and Characterization of Two Brown Dwarfs Around M Dwarfs*
Searching for GEMS: Discovery and Characterization of Two Brown Dwarfs Around M Dwarfs* Open
Brown dwarfs bridge the gap between stars and planets, providing valuable insight into both planetary and stellar-formation mechanisms. Yet the census of transiting brown-dwarf companions, in particular around M-dwarf stars, remains incomp…
View article: Searching for GEMS: TOI-5688 A b, a Low-density Giant Orbiting a High-metallicity Early M-dwarf*
Searching for GEMS: TOI-5688 A b, a Low-density Giant Orbiting a High-metallicity Early M-dwarf* Open
We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets ( R ≳ 8 R ⊕ ) through the Searching for Giant Exopl…
View article: Gaia-4b and 5b: Radial Velocity Confirmation of Gaia Astrometric Orbital Solutions Reveal a Massive Planet and a Brown Dwarf Orbiting Low-mass Stars
Gaia-4b and 5b: Radial Velocity Confirmation of Gaia Astrometric Orbital Solutions Reveal a Massive Planet and a Brown Dwarf Orbiting Low-mass Stars Open
Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity (RV) data are needed for definitive confirmation. Here we present RV follow-up observations of 28 M an…
View article: Searching for GEMS: Discovery and Characterization of Two Brown Dwarfs Around M Dwarfs
Searching for GEMS: Discovery and Characterization of Two Brown Dwarfs Around M Dwarfs Open
Brown dwarfs bridge the gap between stars and planets, providing valuable insight into both planetary and stellar formation mechanisms. Yet the census of transiting brown dwarf companions, in particular around M dwarf stars, remains incomp…
View article: TOI-2458 b: A mini-Neptune consistent with in situ hot Jupiter formation
TOI-2458 b: A mini-Neptune consistent with in situ hot Jupiter formation Open
We report on the discovery and spectroscopic confirmation of TOI-2458 b, a transiting mini-Neptune around an F-type star leaving the main-sequence with a mass of M ★ = 1.05 ± 0.03 M ⊙ , a radius of R ★ = 1.31 ± 0.03 R ⊙ , an effective temp…
View article: Radii, masses, and transit-timing variations of the three-planet system orbiting the naked-eye star TOI-396
Radii, masses, and transit-timing variations of the three-planet system orbiting the naked-eye star TOI-396 Open
Context . TOI-396 is an F6 V bright naked-eye star ( V ≈ 6.4) orbited by three small ( R p ≈ 2 R ⊕ ) transiting planets discovered thanks to space-based photometry from two TESS sectors. The orbital periods of the two innermost planets, na…
View article: Searching for GEMS: TOI-6383Ab, a Giant Planet Transiting an M3-dwarf Star in a Binary System*
Searching for GEMS: TOI-6383Ab, a Giant Planet Transiting an M3-dwarf Star in a Binary System* Open
We report on the discovery of a transiting giant planet around the 3500 K M3-dwarf star TOI-6383A located 172 pc from Earth. It was detected by the Transiting Exoplanet Survey Satellite and confirmed by a combination of ground-based follow…
View article: Searching for GEMS: Two Super-Jupiters around M-dwarfs -- Signatures of Instability or Accretion?
Searching for GEMS: Two Super-Jupiters around M-dwarfs -- Signatures of Instability or Accretion? Open
We present the discovery of TOI-6303b and TOI-6330b, two massive transiting super-Jupiters orbiting a M0 and a M2 star respectively, as part of the Searching for GEMS survey. These were detected by TESS and then confirmed via ground-based …
View article: TOI–757 b: an eccentric transiting mini–Neptune on a 17.5–d orbit
TOI–757 b: an eccentric transiting mini–Neptune on a 17.5–d orbit Open
We report the spectroscopic confirmation and fundamental properties of TOI$-$757 b, a mini$-$Neptune on a 17.5$-$d orbit transiting a bright star ($V\, =\, 9.7$ mag) discovered by the TESS mission. We acquired high$-$precision radial veloc…
View article: Searching for GEMS: Characterizing Six Giant Planets Around Cool Dwarfs
Searching for GEMS: Characterizing Six Giant Planets Around Cool Dwarfs Open
Transiting giant exoplanets around M-dwarf stars (GEMS) are rare, owing to the low-mass host stars. However, the all-sky coverage of TESS has enabled the detection of an increasingly large number of them to enable statistical surveys like …
View article: Gaia-4b and 5b: Radial Velocity Confirmation of Gaia Astrometric Orbital Solutions Reveal a Massive Planet and a Brown Dwarf Orbiting Low-mass Stars
Gaia-4b and 5b: Radial Velocity Confirmation of Gaia Astrometric Orbital Solutions Reveal a Massive Planet and a Brown Dwarf Orbiting Low-mass Stars Open
Gaia astrometry of nearby stars is precise enough to detect the tiny displacements induced by substellar companions, but radial velocity data are needed for definitive confirmation. Here we present radial velocity follow-up observations of…
View article: TOI-2458 b: A mini-Neptune consistent with in situ hot Jupiter formation
TOI-2458 b: A mini-Neptune consistent with in situ hot Jupiter formation Open
We report on the discovery and spectroscopic confirmation of TOI-2458 b, a transiting mini-Neptune around an F-type star leaving the main-sequence with a mass of $M_\star=1.05 \pm 0.03$ M$_{\odot}$, a radius of $R_\star=1.31 \pm 0.03$ R$_{…
View article: Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf
Searching for GEMS: TOI-5688 A b, a low-density giant orbiting a high-metallicity early M-dwarf Open
We present the discovery of a low-density planet orbiting the high-metallicity early M-dwarf TOI-5688 A b. This planet was characterized as part of the search for transiting giant planets ($R \gtrsim8$ M${}_\oplus$) through the Searching f…
View article: Astrometry and Precise Radial Velocities Yield a Complete Orbital Solution for the Nearby Eccentric Brown Dwarf LHS 1610 b
Astrometry and Precise Radial Velocities Yield a Complete Orbital Solution for the Nearby Eccentric Brown Dwarf LHS 1610 b Open
The LHS 1610 system consists of a nearby ( d = 9.7 pc) M5 dwarf hosting a candidate brown dwarf companion in a 10.6 days, eccentric ( e ∼ 0.37) orbit. We confirm this brown dwarf designation and estimate its mass ( M Jup ) and in…
View article: Mass determination of two Jupiter-sized planets orbiting slightly evolved stars: TOI-2420 b and TOI-2485 b
Mass determination of two Jupiter-sized planets orbiting slightly evolved stars: TOI-2420 b and TOI-2485 b Open
Context. Hot and warm Jupiters might have undergone the same formation and evolution path, but the two populations exhibit different distributions of orbital parameters. This challenges our understanding of their actual origin. Aims. We re…
View article: Mass determination of two Jupiter-sized planets orbiting slightly evolved stars: TOI-2420 b and TOI-2485 b
Mass determination of two Jupiter-sized planets orbiting slightly evolved stars: TOI-2420 b and TOI-2485 b Open
Hot and warm Jupiters might have undergone the same formation and evolution path, but the two populations exhibit different distributions of orbital parameters, challenging our understanding on their actual origin. The present work, which …