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The Milky Way Tomography with SDSS. III. Stellar Kinematics
Brewington, Howard; Schneider, Donald P.; Majewski, Steven R. +54 more
We study Milky Way kinematics using a sample of 18.8 million main-sequence stars with r < 20 and proper-motion measurements derived from Sloan Digital Sky Survey (SDSS) and POSS astrometry, including ~170,000 stars with radial-velocity measurements from the SDSS spectroscopic survey. Distances to stars are determined using a photometric-paralla…
The Velocity Distribution of Nearby Stars from Hipparcos Data. II. The Nature of the Low-velocity Moving Groups
Bovy, Jo; Hogg, David W.
The velocity distribution of nearby stars (lsim100 pc) contains many overdensities or "moving groups," clumps of comoving stars, that are inconsistent with the standard assumption of an axisymmetric, time-independent, and steady-state Galaxy. We study the age and metallicity properties of the low-velocity moving groups based on the reconstruction …
Angular Diameters and Effective Temperatures of 25 K Giant Stars from the CHARA Array
Guenther, Eike W.; Hatzes, Artie P.; Goldfinger, P. J. +10 more
Using Georgia State University's Center for High Angular Resolution Astronomy Array interferometer, we measured angular diameters for 25 giant stars, six of which host exoplanets. The combination of these measurements and Hipparcos parallaxes produces physical linear radii for the sample. Except for two outliers, our values match angular diameters…
The Nature of the Hyper-Runaway Candidate Hip 60350
Przybilla, Norbert; Irrgang, Andreas; Heber, Ulrich +2 more
Young, massive stars in the Galactic halo are widely supposed to be the result of an ejection event from the Galactic disk forcing some stars to leave their place of birth as so-called runaway stars. Here, we present a detailed spectroscopic and kinematic analysis of the runaway B star HIP 60350 to determine which runaway scenario—a supernova expl…
Taming the Invisible Monster: System Parameter Constraints for epsilon Aurigae from the Far-ultraviolet to the Mid-infrared
Stencel, R. E.; Hoard, D. W.; Howell, S. B.
We have assembled new Spitzer Space Telescope IRAC observations of the mysterious binary star epsilon Aurigae, along with archival far-ultraviolet to mid-infrared data, to form an unprecedented spectral energy distribution (SED) spanning 3 orders of magnitude in wavelength from 0.1 µm to 100 µm. The observed SED can be reproduced using…
Lithium Abundance in Solar-type Stars with Low Chromospheric Activity: Application to the Search for Maunder Minimum Analogs
Tytler, David; Lubin, Dan; Kirkman, David
We use measurements of lithium abundance to examine the evolutionary history of stars frequently believed to be in a Maunder minimum (MM) state due to their low chromospheric activity. In a sample whose main-sequence membership has been verified using Hipparcos parallax data, we find that stars with very low chromospheric activity log R'HK