Search Publications
Gaia Assorted Mass Binaries Long Excluded from SLoWPoKES (GAMBLES): Identifying Ultra-wide Binary Pairs with Components of Diverse Mass
Stassun, Keivan G.; Oelkers, Ryan J.; Dhital, Saurav
The formation and evolution of binary star systems are some of the remaining key questions in modern astronomy. Wide binary pairs (separations >103 au) are particularly intriguing because their low binding energies make it difficult for the stars to stay gravitationally bound over extended timescales, and thus to probe the dynamics o…
The Star Blended with the MOA-2008-BLG-310 Source Is Not the Exoplanet Host Star
Bennett, D. P.; Anderson, J.; Gould, A. +7 more
High-resolution Hubble Space Telescope (HST) image analysis of the MOA-2008-BLG-310 microlens system indicates that the excess flux at the location of the source found in the discovery paper cannot primarily be due to the lens star because it does not match the lens-source relative proper motion, {µ }{rel}, predicted by the microl…
Characterization of the VVV Survey RR Lyrae Population across the Southern Galactic Plane
Valenti, Elena; Minniti, Dante; Rejkuba, Marina +14 more
Deep near-IR images from the VISTA Variables in the Vía Láctea (VVV) Survey were used to search for RR Lyrae stars in the Southern Galactic plane. A sizable sample of 404 RR Lyrae of type ab stars was identified across a thin slice of the fourth Galactic quadrant (295° < ℓ < 350°, -2.°24 < b < -1.°05). The sample’s distance distributio…
The Structure of Chariklo’s Rings from Stellar Occultations
Colas, F.; Bérard, D.; Kervella, P. +79 more
Two narrow and dense rings (called C1R and C2R) were discovered around the Centaur object (10199) Chariklo during a stellar occultation observed on 2013 June 3. Following this discovery, we planned observations of several occultations by Chariklo’s system in order to better characterize the physical properties of the ring and main body. Here, we u…
High-resolution Spectroscopy of Extremely Metal-poor Stars from SDSS/SEGUE. III. Unevolved Stars with [Fe/H] ≲ -3.5
Honda, Satoshi; Beers, Timothy C.; Lee, Young Sun +2 more
We present elemental abundances for eight unevolved extremely metal-poor (EMP) stars with {T}{eff}> 5500 {{K}}, among which seven have [{Fe}/{{H}}]< -3.5. The sample is selected from the Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration (SDSS/SEGUE) and our previous high-resolution spectroscopic f…
CCD Parallaxes for 309 Late-type Dwarfs and Subdwarfs
Harris, Hugh C.; Vrba, Frederick J.; Munn, Jeffrey A. +16 more
New, updated, and/or revised CCD parallaxes determined with the Strand Astrometric Reflector at the Naval Observatory Flagstaff Station are presented. Included are results for 309 late-type dwarf and subdwarf stars observed over the 30+ years that the program operated. For 124 of the stars, parallax determinations from other investigators have alr…
The Discovery of λ Bootis Stars: The Southern Survey I
Neff, J. E.; Cheng, K. -P.; Gray, R. O. +5 more
The λ Boo stars are a class of chemically peculiar Population I A-type stars characterized by under-abundances of the refractory elements, but near-solar abundances of carbon, nitrogen, oxygen, and sulfur. There is some evidence that λ Boo stars have higher frequencies of “bright” debris disks than normal A-type stars. The discovery of four exopla…
The Young Substellar Companion ROXs 12 B: Near-infrared Spectrum, System Architecture, and Spin-Orbit Misalignment
Vanderburg, Andrew; Brogi, Matteo; Knutson, Heather A. +8 more
ROXs 12 (2MASS J16262803-2526477) is a young star hosting a directly imaged companion near the deuterium-burning limit. We present a suite of spectroscopic, imaging, and time-series observations to characterize the physical and environmental properties of this system. Moderate-resolution near-infrared spectroscopy of ROXs 12 B from Gemini-North/NI…
Orbits for 18 Visual Binaries and Two Double-line Spectroscopic Binaries Observed with HRCAM on the CTIO SOAR 4 m Telescope, Using a New Bayesian Orbit Code Based on Markov Chain Monte Carlo
Mendez, Rene A.; Claveria, Ruben M.; Orchard, Marcos E. +1 more
We present orbital elements and mass sums for 18 visual binary stars of spectral types B to K (five of which are new orbits) with periods ranging from 20 to more than 500 yr. For two double-line spectroscopic binaries with no previous orbits, the individual component masses, using combined astrometric and radial velocity data, have a formal uncert…
The Pan-Pacific Planet Search. VII. The Most Eccentric Planet Orbiting a Giant Star
Marshall, J. P.; Mustill, A. J.; Kane, Stephen R. +9 more
Radial velocity observations from three instruments reveal the presence of a 4 MJup planet candidate orbiting the K giant HD 76920. HD 76920b has an orbital eccentricity of 0.856 ± 0.009, making it the most eccentric planet known to orbit an evolved star. There is no indication that HD 76920 has an unseen binary companion, suggesting a …