Search Publications
Identifying Galactic Halo Substructure in 6D Phase Space Using ∼13,000 LAMOST K Giants
Tian, Hao; Zhao, Gang; Li, Chengdong +6 more
We construct a large halo K-giant sample by combining the positions, distances, radial velocities, and metallicities of over 13,000 LAMOST DR5 halo K giants with the Gaia DR2 proper motions, which covers a Galactocentric distance range of 5-120 kpc. Using a position-velocity clustering estimator (the 6Distance), we statistically quantify the prese…
TESS Habitable Zone Star Catalog
Stassun, K.; Kaltenegger, L.; Pepper, J. +1 more
We present the Transiting Exoplanet Survey Satellite (TESS) Habitable Zone Stars Catalog, a list of 1822 nearby stars with a TESS magnitude brighter than T = 12 and reliable distances from Gaia DR2, around which the NASA’s TESS mission can detect transiting planets, which receive Earth-like irradiation. For all those stars TESS is sensitive down t…
The Unexpected Spectrum of the Innermost Ejecta of the Red Hypergiant VY CMa
Humphreys, Roberta M.; Jones, Terry J.; Gordon, Michael S. +6 more
Hubble Space Telescope/STIS spectra of the small clumps and filaments closest to the central star in VY CMa reveal that the very strong K I emission and TiO and VO molecular emission, long thought to form in a dusty circumstellar shell, actually originate in a few small clumps hundreds of au from the star. The K I lines are 10-20 times stronger in…
Multiwavelength Period-Luminosity and Period-Luminosity-Color Relations at Maximum Light for Mira Variables in the Magellanic Clouds
Matsunaga, Noriyuki; de Grijs, Richard; Rejkuba, Marina +8 more
We present Period-Luminosity and Period-Luminosity-Color relations at maximum light for Mira variables in the Magellanic Clouds using time-series data from the Optical Gravitational Lensing Experiment (OGLE-III) and Gaia data release 2. The maximum-light relations exhibit a scatter typically up to ∼30% smaller than their mean-light counterparts. T…
Asymmetric Drift in the Andromeda Galaxy (M31) as a Function of Stellar Age
Williams, Benjamin F.; Gilbert, Karoline M.; Chemin, Laurent +5 more
We analyze the kinematics of Andromeda’s disk as a function of stellar age by using photometry from the Panchromatic Hubble Andromeda Treasury survey and spectroscopy from the Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo survey. We use H I 21 cm and CO (J=1\to 0) data to examine the difference between the deprojected rotatio…
The R-Process Alliance: Discovery of a Low-α, r-process-enhanced Metal-poor Star in the Galactic Halo
Grebel, Eva K.; Steinmetz, Matthias; Beers, Timothy C. +24 more
A new moderately r-process-enhanced metal-poor star, RAVE J093730.5-062655, has been identified in the Milky Way halo as part of an ongoing survey by the R-Process Alliance. The temperature and surface gravity indicate that J0937-0626 is likely a horizontal branch star. At [Fe/H] = -1.86, J0937-0626 is found to have subsolar [X/Fe] ratios for near…
Bidirectional Reconnection Outflows in an Active Region
Aulanier, Guillaume; Schmieder, Brigitte; Masson, Sophie +4 more
We report on bidirectional coronal reconnection outflows reaching ±200 km s-1 as observed in an active region with the Si IV and C II spectra of the Interface Region Imaging Spectrograph (IRIS). The evolution of the active region with an emerging flux, a failed filament eruption, and a jet is followed in Solar Dynamical Observatory (SDO…
The Disappearing Solar Filament of 2013 September 29 and Its Large Associated Proton Event: Implications for Particle Acceleration at the Sun
Kahler, S. W.; Shimojo, M.; Cliver, E. W. +1 more
We present observations of a notable example of a disappearing solar filament (DSF) on 2013 September 29 that was associated with a large solar proton event (SPE) and discuss this event in the context of four recent studies that compare flare and SPE size parameters. The DSF-associated flare was characterized by weak radio and soft X-ray emissions…
High-resolution Spectroscopic Analysis of a Large Sample of Li-rich Giants Found By LAMOST
Shi, Jianrong; Zhao, Gang; Blanco-Cuaresma, S. +6 more
The discovery of Li-rich giants has introduced a new challenge for standard stellar evolution models. To resolve this issue, the number of this type of object has been rapidly increased through the development of worldwide surveys. Taking advantage of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope survey, 44 new Li-rich giants are r…
Micrometeoroid Events in LISA Pathfinder
Mendes, L.; Madden, S.; Russano, G. +121 more
The zodiacal dust complex, a population of dust and small particles that pervades the solar system, provides important insight into the formation and dynamics of planets, comets, asteroids, and other bodies. We present a new set of data obtained from direct measurements of momentum transfer to a spacecraft from individual particle impacts. This te…