Search Publications
The Origin of High-velocity Stars Considering the Impact of the Large Magellanic Cloud
Shi, Jianrong; Huang, Yang; Ma, Jun +5 more
Utilizing astrometric parameters sourced from Gaia Data Release 3 and radial velocities obtained from various spectroscopic surveys, we identify 519 high-velocity stars (HiVels) with a total velocity in the Galactocentric rest frame greater than 70% of their local escape velocity under the Gala MilkyWayPotential. Our analysis reveals that the majo…
GJ 238 b: A 0.57 Earth Radius Planet Orbiting an M2.5 Dwarf Star at 15.2 pc
Hellier, Coel; Stassun, Keivan G.; Howell, Steve B. +30 more
We report the discovery of the transiting planet GJ 238 b, with a radius of 0.566 ± 0.014 R ⊕ (1.064 ± 0.026 times the radius of Mars) and an orbital period of 1.74 days. The transit signal was detected by the TESS mission and designated TOI-486.01. The star's position close to the southern ecliptic pole allows for almost continuous obs…
Using AI for Wave-front Estimation with the Rubin Observatory Active Optics System
Thomas, Sandrine; Connolly, Andrew J.; Suberlak, Krzysztof +6 more
The Vera C. Rubin Observatory will, over a period of 10 yr, repeatedly survey the southern sky. To ensure that images generated by Rubin meet the quality requirements for precision science, the observatory will use an active-optics system (AOS) to correct for alignment and mirror surface perturbations introduced by gravity and temperature gradient…
Candidates for Substellar Members of the Orion Nebula Cluster from JWST/NIRCam
Luhman, K. L.
In 2022, the James Webb Space Telescope (JWST) obtained 1–5 µm images of the center of the Orion Nebula Cluster (ONC). I have analyzed these data in an attempt to search for substellar members of the cluster. Using a pair of color–color diagrams, I have identified >200 brown dwarf candidates that lack spectral classifications. Some of the…
Stellar Variability and Distance Indicators in the Near-infrared in Nearby Galaxies. I. RR Lyrae and Anomalous Cepheids in Draco Dwarf Spheroidal
Marconi, Marcella; Ripepi, Vincenzo; Rejkuba, Marina +4 more
The Draco Dwarf spheroidal (dSph) galaxy is one of the nearest and the most dark-matter-dominated satellites of the Milky Way. We obtained multiepoch near-infrared (NIR, JHK s ) observations of the central region of Draco dSph covering a sky area of ∼21' × 21' using the WIRCam instrument at the 3.6 m Canada–France–Hawaii Telescope. Hom…
Orbital and Atmospheric Characterization of the 1RXS J034231.8+121622 System using High-resolution Spectroscopy Confirms that the Companion is a Low-mass Star
Do Ó, Clarissa R.; Fitzgerald, Michael P.; López, Ronald A. +33 more
The 1RXS J034231.8+121622 system consists of an M dwarf primary and a directly imaged low-mass stellar companion. We use high-resolution spectroscopic data from Keck/KPIC to estimate the objects' atmospheric parameters and radial velocities (RVs). Using PHOENIX stellar models, we find that the primary has a temperature of 3460 ± 50 K and a metalli…
Surviving Tidal Tails Around the Milky Way Bulge Globular Cluster NGC 6355
Piatti, Andrés E.
We present results of the analysis of a set of images obtained in the field of the Milky Way bulge globular cluster NGC 6355 using the Dark Energy Camera, which is attached to the 4 m Blanco telescope of the Cerro-Tololo Interamerican Observatory. We dealt with a heavy differential absorption across the observed field, a crowded field star populat…
Discovery of 118 New Ultracool Dwarf Candidates Using Machine-learning Techniques
Tang, Shih-Yun; Meisner, Aaron M.; Kirkpatrick, J. Davy +45 more
We present the discovery of 118 new ultracool dwarf candidates, discovered using a new machine-learning tool, named SMDET, applied to time-series images from the Wide-field Infrared Survey Explorer. We gathered photometric and astrometric data to estimate each candidate's spectral type, distance, and tangential velocity. This sample has a photomet…
A Self-consistent Data-driven Model for Determining Stellar Parameters from Optical and Near-infrared Spectra
Stassun, Keivan G.; Kounkel, Marina; Chandra, Vedant +3 more
Data-driven models, which apply machine learning to infer physical properties from large quantities of data, have become increasingly important for extracting stellar properties from spectra. In general, these methods have been applied to data in one wavelength regime or another. For example, APOGEE Net has been applied to near-IR spectra from the…
Deepest Limits on Scattered Light Emission from the Epsilon Eridani Inner Debris Disk with HST/STIS
Stark, Christopher C.; Debes, John H.; Hom, Justin +9 more
Epsilon Eridani is one of the first debris disk systems detected by the Infrared Astronomical Satellite. However, the system has thus far eluded detection in scattered light with no components having been directly imaged. Its similarity to a relatively young solar system combined with its proximity makes it an excellent candidate to further our un…