activity
20222026
most citedTwo Candidate KH 15D-like Systems from the Zwicky Transient Facility

14 citations · 36 across the 23 of their papers we have counts for

collaborators

26 papers

astro-ph.EP2026

Does HD 3167 Have Planets with Perpendicular Orbits?

Joshua N. Winn, Jack Lubin, Guðmundur Stefánsson +5

The two transiting planets of HD 3167 were reported to follow nearly perpendicular paths, with the inner orbit aligned with the stellar equator and the outer orbit nearly polar. Th…

astro-ph.EP2026

Evidence for an Extended Hydrogen Outflow on WASP-12 b

Morgan Saidel, Shreyas Vissapragada, Heather A. Knutson +6

Recent observations of atmospheric escape from planets orbiting early-type stars indicate that planets with higher Roche filling factors have significantly higher mass loss rates.…

astro-ph.EP2026

POSEIDON III: The Aligned Orbit of the Hot Neptune Around the Hot Star WASP-195

Juan I. Espinoza-Retamal, Joshua N. Winn, Rafael Brahm +33

Stellar obliquities provide important clues as to the formation and migration histories of planetary systems, but measurements remain scarce for Neptune-mass planets, especially th…

astro-ph.EP2026

Transiting Planetary Systems with Distant Giant Companions Remain Moderately Coplanar

Guang-Yao Xiao, Huan-Yu Teng, Xiumin Huang +4

The mutual inclination between inner planets and distant giant companions provides an important probe of planetary system formation and dynamical evolution, yet direct measurements…

astro-ph.EP2026

Spin-Orbit Alignment of Two Neptune-size Planets Younger than 500 Myr: TOI-560 b and TOI-5082 b

Elina Y. Zhang, Fei Dai, Andrew W. Howard +25

Stellar obliquity measurements provide a direct probe of planetary system dynamics, but remain sparse for Neptune-size planets, particularly at young ages. We present Rossiter-McLa…

astro-ph.EP2026

The KPF-SLOPE Survey - Small, Compact Multi-Planet Systems Appear Spin-Orbit Aligned

Luke B. Handley, Andrew W. Howard, Fei Dai +16

The angle between stellar spin axes and planetary orbits -- stellar obliquity -- probes the dynamics of planetary migration and evolution. The obliquities of giant planets have bee…

astro-ph.SR2026

Stars stably accreting from substellar objects

Aaron Householder, Kaitlyn Shin, Kevin B. Burdge +11

Substellar objects such as brown dwarfs and planets are generally expected to remain detached from their main-sequence host stars unless orbital decay or stellar expansion brings t…

astro-ph.EP2025

The KPF SURFS-UP Survey I: Transmission Spectroscopy of WASP-76 b

Aaron Householder, Fei Dai, Aurora Kesseli +25

We introduce the KPF SURFS-UP (Spectroscopy of the Upper-atmospheres and ReFractory Species in Ultra-hot Planets) Survey, a high-resolution survey to investigate the atmospheric co…

astro-ph.EP2025

The Polar Orbit of TOI-2374 b, a Planet in the Neptunian Ridge

Samuel W. Yee, Patrick Tamburo, Gudmundur Stefánsson +11

The ``Neptunian ridge'' is a recently identified peak in the frequency of planets with sizes between that of Neptune and Saturn orbiting their host stars with periods between 3 and…

astro-ph.EP2025

TOI-880 is an Aligned, Coplanar, Multi-planet System

Elina Y. Zhang, Huan-Yu Teng, Fei Dai +22

Although many cases of stellar spin-orbit misalignment are known, it is usually unclear whether a single planet's orbit was tilted or if the entire protoplanetary disk was misalign…

astro-ph.EP2025★ 1 cited

TOI-1259Ab: A Warm Jupiter Orbiting a K-dwarf White-Dwarf Binary is on a Well-aligned Orbit

Hugo Veldhuis, Juan I. Espinoza-Retamal, Gudmundur Stefansson +21

The evolution of one member of a stellar binary into a white dwarf has been proposed as a mechanism that triggers the formation of close-in gas giant planets. The star's asymmetric…

astro-ph.EP2025

A Hot Jupiter with a Retrograde Orbit around a Sun-like Star and a Toy Model of Hot Jupiters in Wide Binary Star Systems

Steven Giacalone, Andrew W. Howard, Ryan A. Rubenzahl +21

We report an observation of a transit of the hot Jupiter (HJ) KELT-23A b with the Keck Planet Finder spectrograph and a measurement of the sky-projected obliquity () of its Sun-…

astro-ph.EP2025

Stellar Obliquity of the Ultra-Short-Period Planet System HD 93963

Huan-Yu Teng, Fei Dai, Andrew W. Howard +24

We report an observation of the Rossiter-McLaughlin (RM) effect of the transiting planet HD 93963 Ac, a mini-Neptune planet orbiting a G0-type star with an orbital period of $P_{\r…

astro-ph.SR2025

K-dwarf Radius Inflation and a 10-Gyr Spin-down Clock Unveiled through Asteroseismology of HD 219134 from the Keck Planet Finder

Yaguang Li, Daniel Huber, J. M. Joel Ong +26

We present the first asteroseismic analysis of the K3\,V planet host HD~219134, based on four consecutive nights of radial velocities collected with the Keck Planet Finder. We appl…

astro-ph.EP2025

TOI-6324b: An Earth-Mass Ultra-Short-Period Planet Transiting a Nearby M Dwarf

Rena A. Lee, Fei Dai, Andrew W. Howard +71

We report the confirmation of TOI-6324 b, an Earth-sized (1.059 0.041 R) ultra-short-period (USP) planet orbiting a nearby (20 pc) M dwarf. Using the newly com…

astro-ph.EP2025

Short-Period Small Planets with High Mutual Inclinations are more Common around Metal-Rich Stars

Xinyan Hua, Sharon Xuesong Wang, Dongsheng An +7

We present a correlation between the stellar metallicities and the mutual inclinations of multi-planet systems hosting short-period small planets (a/Rs<12, Rp<4Re). We analyzed 89…

astro-ph.EP2024★ 1 cited

The Compositions of Rocky Planets in Close-in Orbits Tend to be Earth-Like

Casey L. Brinkman, Lauren M. Weiss, Daniel Huber +54

Hundreds of exoplanets between 1-1.8 times the size of the Earth have been discovered on close in orbits. However, these planets show such a diversity in densities that some appear…

astro-ph.EP2024

The HD 191939 Exoplanet System is Well-Aligned and Flat

Jack Lubin, Erik A. Petigura, Judah Van Zandt +25

We report the sky-projected spin-orbit angle for HD 191939 b, the innermost planet in a 6 planet system, using Keck/KPF to detect the Rossiter-McLaughlin (RM) effect. Planet b…

astro-ph.SR2024

Asteroseismology of the Nearby K-Dwarf Draconis using the Keck Planet Finder and TESS

Marc Hon, Daniel Huber, Yaguang Li +76

Asteroseismology of dwarf stars cooler than the Sun is very challenging due to the low amplitudes and rapid timescales of oscillations. Here, we present the asteroseismic detection…

astro-ph.EP2024

KPF Confirms a Polar Orbit for KELT-18 b

Ryan A. Rubenzahl, Fei Dai, Samuel Halverson +24

We present the first spectroscopic transit results from the newly commissioned Keck Planet Finder on the Keck-I telescope at W. M. Keck Observatory. We observed a transit of KELT-1…

astro-ph.EP2024

Obliquity Constraints for the Extremely Eccentric Sub-Saturn Kepler-1656 b

Ryan A. Rubenzahl, Andrew W. Howard, Samuel Halverson +25

The orbits of close-in exoplanets provide clues to their formation and evolutionary history. Many close-in exoplanets likely formed far out in their protoplanetary disks and migrat…

astro-ph.EP2024

An Earth-sized Planet on the Verge of Tidal Disruption

Fei Dai, Andrew W. Howard, Samuel Halverson +95

TOI-6255~b (GJ 4256) is an Earth-sized planet (1.079 ) with an orbital period of only 5.7 hours. With the newly commissioned Keck Planet Finder (KPF) and CARMEN…

astro-ph.EP2024

A Testbed for Tidal Migration: the 3D Architecture of an Eccentric Hot Jupiter HD 118203 b Accompanied by a Possibly Aligned Outer Giant Planet

Jingwen Zhang, Daniel Huber, Lauren M. Weiss +31

Characterizing outer companions to hot Jupiters plays a crucial role in deciphering their origins. We present the discovery of a long-period giant planet, HD 118203 c ($m_{c}=11.79…

astro-ph.EP2024★ 13 cited

The OATMEAL Survey. I. Low Stellar Obliquity in the Transiting Brown Dwarf System GPX-1

Steven Giacalone, Fei Dai, J. J. Zanazzi +31

We introduce the OATMEAL survey, an effort to measure the obliquities of stars with transiting brown dwarf companions. We observed a transit of the close-in ($P_{\rm orb} = 1.74 \,…