Search Publications
URAT South Parallax Results
Jao, Wei-Chun; Finch, Charlie T.; Zacharias, Norbert
We present 916 trigonometric parallaxes and proper motions of newly discovered nearby stars from the United States Naval Observatory Robotic Astrometric Telescope (URAT). Observations were taken at the Cerro Tololo Interamerican Observatory over a 2-year period from 2015 to 2017 October covering the entire sky south of about +25° decl. SPM4 and UC…
Deep Hubble Space Telescope Imaging of Globular Clusters toward the Galactic Bulge: Observations, Data Reduction, and Color-magnitude Diagrams
Cohen, Roger E.; Sarajedini, Ata; Hempel, Maren +5 more
The Galactic globular clusters (GGCs) located toward the Galactic bulge have generally been excluded from large-scale photometric GGC surveys due to severe total and differential extinction. Here we present an overview of a Hubble Space Telescope (HST) program designed to obtain deep, high spatial resolution multiband imaging of 16 poorly studied …
V1224 Cas: An EL CVn-type Eclipsing Binary Consisting of a Helium White Dwarf Precursor and a Delta Scuti Pulsator
Deng, Licai; Zhang, Xiaobin; Wang, Kun +3 more
We report the discovery of a new eclipsing EL CVn-type binary, consisting of a δ Sct-type pulsator and a thermally bloated low-mass pre-He white dwarf (WD). Spectroscopy and time-series BV photometry of V1224 Cas were carried out. The spectroscopy reveals a spectral type of A3 for the star. Light curve modeling indicates that V1224 Cas is a short-…
Kinetic Tomography. II. A Second Method for Mapping the Velocity Field of the Milky Way Interstellar Medium and a Comparison with Spiral Structure Models
Peek, J. E. G.; Tchernyshyov, Kirill; Zasowski, Gail
In this work, we derive a spatially resolved map of the line-of-sight velocity of the interstellar medium and use it, along with a second map of line-of-sight velocity from Paper I of this series, to determine the nature of the gaseous spiral structure in the Milky Way (MW). This map is derived from measurements of the 1.527 µm diffuse inter…
A General Method for Assessing the Origin of Interstellar Small Bodies: The Case of 1I/2017 U1 (‘Oumuamua)
Zuluaga, Jorge I.; Sánchez-Hernández, Oscar; Sucerquia, Mario +1 more
With the advent of more and deeper sky surveys, the discovery of interstellar small objects entering into the solar system has been finally possible. In 2017 October 19, using observations of the Pan-STARRS survey, a fast moving object, now officially named 1I/2017 U1 (‘Oumuamua), was discovered in a heliocentric unbound trajectory, suggesting an …
SCExAO/CHARIS Near-IR High-contrast Imaging and Integral Field Spectroscopy of the HIP 79977 Debris Disk
Currie, Thayne; Kwon, Jungmi; Tamura, Motohide +13 more
We present new, near-infrared (1.1-2.4 µm) high-contrast imaging of the bright debris disk surrounding HIP 79977 with the Subaru Coronagraphic Extreme Adaptive Optics system (SCExAO) coupled with the CHARIS integral field spectrograph. SCExAO/CHARIS resolves the disk down to smaller angular separations of (0.″11 r ∼ 14 au) and at a higher si…
Robust Transiting Exoplanet Radii in the Presence of Starspots from Ingress and Egress Durations
Hawley, Suzanne L.; Hebb, Leslie; Agol, Eric +1 more
We typically measure the radii of transiting exoplanets from the transit depth, which are given by the ratio of cross-sectional areas of the planet and star. However, if a star has dark starspots (or bright regions) distributed throughout the transit chord, the transit depth will be biased toward smaller (larger) values, and thus the inferred plan…
Two Warm, Low-density Sub-Jovian Planets Orbiting Bright Stars in K2 Campaigns 13 and 14
Butler, R. Paul; Vanderburg, Andrew; Bieryla, Allyson +25 more
We report the discovery of two planets transiting the bright stars HD 89345 (EPIC 248777106, V = 9.376, K = 7.721) in K2 Campaign 14 and HD 286123 (EPIC 247098361, V = 9.822, K = 8.434) in K2 Campaign 13. Both stars are G-type stars, one of which is at or near the end of its main-sequence lifetime, and the other is just over halfway through its ma…
Diffuse X-Ray-emitting Gas in Major Mergers
Soria, Roberto; Struck, Curtis; Smith, Beverly J. +5 more
Using archived data from the Chandra X-ray telescope, we have extracted the diffuse X-ray emission from 49 equal-mass interacting/merging galaxy pairs in a merger sequence, from widely separated pairs to merger remnants. After the removal of contributions from unresolved point sources, we compared the diffuse thermal X-ray luminosity from hot gas …
A Bayesian Framework for Exoplanet Direct Detection and Non-detection
De Rosa, Robert J.; Macintosh, Bruce; Nielsen, Eric L. +9 more
Rigorously quantifying the information in high-contrast imaging data is important for informing follow-up strategies to confirm the substellar nature of a point source, constraining theoretical models of planet-disk interactions, and deriving planet occurrence rates. However, within the exoplanet direct imaging community, non-detections have almos…