Search Publications
Noncircular Motions in the Outer Perseus Spiral Arm
Menten, Karl M.; Reid, Mark J.; Sakai, Nobuyuki +2 more
We report measurements of parallax and proper motion for five 6.7 GHz methanol maser sources in the outer regions of the Perseus arm as part of the BeSSeL Survey of the Galaxy. By combining our results with previous astrometric results, we determine an average spiral arm pitch angle of 9.°2 ± 1.°5 and an arm width of 0.39 kpc for this spiral arm. …
Signatures of Tidal Disruption in Ultra-faint Dwarf Galaxies: A Combined HST, Gaia, and MMT/Hectochelle Study of Leo V
Caldwell, Nelson; Strader, Jay; Seth, Anil C. +10 more
The ultra-faint dwarf galaxy Leo V has shown both photometric overdensities and kinematic members at large radii, along with a tentative kinematic gradient, suggesting that it may have undergone a close encounter with the Milky Way. We investigate these signs of disruption through a combination of (i) high precision photometry obtained with the Hu…
Resolved Molecular Gas and Star Formation Properties of the Strongly Lensed z = 2.26 Galaxy SDSS J0901+1814
Wilner, David J.; Keeton, Charles R.; Lutz, Dieter +8 more
We present ∼1″ resolution (∼2 kpc in the source plane) observations of the CO (1-0), CO (3-2), Hα, and [N II] lines in the strongly lensed z = 2.26 star-forming galaxy SDSS J0901+1814. We use these observations to constrain the lensing potential of a foreground group of galaxies, and our source-plane reconstructions indicate that SDSS J0901+1814 i…
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…