Search Publications
More Evidence for Variable Helium Absorption from HD 189733b
Redfield, Seth; Knutson, Heather A.; France, Kevin +5 more
We present a new Keck/NIRSPEC observation of metastable helium absorption from the upper atmosphere of HD 189733b, a hot Jupiter orbiting a nearby moderately active star. We measure an average helium transit depth of 0.420% ± 0.013% integrated over the [-20, 20] km s-1 velocity range. Comparing this measurement to eight previously publi…
A Young, Low-density Stellar Stream in the Milky Way Disk: Theia 456
Kounkel, Marina; Covey, Kevin R.; Agüeros, Marcel A. +4 more
Our view of the variety of stellar structures pervading the local Milky Way has been transformed by the application of clustering algorithms to the Gaia catalog. In particular, several stellar streams have been recently discovered that are comprised of hundreds to thousands of stars and span several hundred parsecs. We analyze one such structure, …
EXPRES. III. Revealing the Stellar Activity Radial Velocity Signature of ϵ Eridani with Photometry and Interferometry
Monnier, John D.; Lanthermann, Cyprien; Anugu, Narsireddy +20 more
The distortions of absorption line profiles caused by photospheric brightness variations on the surfaces of cool, main-sequence stars can mimic or overwhelm radial velocity (RV) shifts due to the presence of exoplanets. The latest generation of precision RV spectrographs aims to detect velocity amplitudes ≲ 10 cm s-1, but requires mitig…
Planets Across Space and Time (PAST). III. Morphology of the Planetary Radius Valley as a Function of Stellar Age and Metallicity in the Galactic Context Revealed by the LAMOST-Gaia-Kepler Sample
Dong, Subo; Zong, Weikai; Zhu, Zi +7 more
The radius valley, a dip in the radius distribution of exoplanets at ~1.9 R ⊕, separates compact rocky super-Earths and sub-Neptunes with lower density. Various hypotheses have been put forward to explain the radius valley. Characterizing the radius valley morphology and its correlation to stellar properties will provide crucial observa…
A Mini-Neptune from TESS and CHEOPS Around the 120 Myr Old AB Dor Member HIP 94235
Latham, David W.; Quinn, Samuel N.; Kane, Stephen R. +36 more
The Transiting Exoplanet Survey Satellite (TESS) mission has enabled discoveries of the brightest transiting planet systems around young stars. These systems are the benchmarks for testing theories of planetary evolution. We report the discovery of a mini-Neptune transiting a bright star in the AB Doradus moving group. HIP 94235 (TOI-4399, TIC 464…
The Open Cluster Chemical Abundances and Mapping Survey. VII. APOGEE DR17 [C/N]-Age Calibration
Bizyaev, Dmitry; Pan, Kaike; Cunha, Katia +11 more
Large-scale surveys open the possibility to investigate Galactic evolution both chemically and kinematically; however, reliable stellar ages remain a major challenge. Detailed chemical information provided by high-resolution spectroscopic surveys of the stars in clusters can be used as a means to calibrate recently developed chemical tools for age…
Orbital Elements and Individual Component Masses from Joint Spectroscopic and Astrometric Data of Double-line Spectroscopic Binaries
Anguita-Aguero, Jennifer; Mendez, Rene A.; Clavería, Rubén M. +1 more
We present orbital elements, orbital parallaxes, and individual component masses for 14 spatially resolved double-line spectroscopic binaries derived doing a simultaneous fit of their visual orbit and radial velocity curve. This was done by means of a Markov Chain Monte Carlo code developed by our group that produces posterior distribution functio…
Revisiting KELT-19Ab, WASP-156b, and WASP-121b in the TESS Era
Chary, Ranga-Ram; Yang, Fan; Liu, Ji-Feng
We present a re-analysis of transit depths of KELT-19Ab, WASP-156b, and WASP-121b, including data from the Transiting Exoplanet Survey Satellite (TESS). The large ~21″ TESS pixels and point-spread function result in significant contamination of the stellar flux by nearby objects. We use Gaia data to fit for and remove this contribution, providing …
Inhomogeneity within Local Interstellar Clouds
Redfield, Seth; Linsky, Jeffrey L.; Ryder, Diana +1 more
Analysis of interstellar absorption lines observed in high-resolution Hubble Space Telescope spectra of nearby stars provides temperatures, turbulent velocities, and kinetic properties of warm interstellar clouds. A new analysis of 97 interstellar-velocity components reveals a wide range of temperatures and turbulent velocities within the Local In…
Dynamical Mass of the Exoplanet Host Star HR 8799
Bowler, Brendan P.; Sepulveda, Aldo G.
HR 8799 is a young A5/F0 star hosting four directly imaged giant planets at wide separations (~16-78 au), which are undergoing orbital motion and have been continuously monitored with adaptive optics imaging since their discovery over a decade ago. We present a dynamical mass of HR 8799 using 130 epochs of relative astrometry of its planets, which…