MAPPING THE LOCAL HALO: STATISTICAL PARALLAX ANALYSIS OF SDSS LOW-MASS SUBDWARFS

作者：Bochanski John J^*; Savcheva Antonia; West Andrew A; Hawley Suzanne L

来源：Astronomical Journal, 2013, 145(2): 40.

DOI：10.1088/0004-6256/145/2/40

• Galaxy: kinematics and dynamics
• methods: statistical
• solar neighborhood
• stars: kinematics and dynamics
• stars: low-mass
• subdwarfs

We present a statistical parallax study of nearly 2000 M subdwarfs with photometry and spectroscopy from the Sloan Digital Sky Survey (SDSS). Statistical parallax analysis yields the mean absolute magnitudes, mean velocities, and velocity ellipsoids for homogenous samples of stars. We selected homogeneous groups of subdwarfs based on their photometric colors and spectral appearance. We examined the color-magnitude relations of low-mass subdwarfs and quantified their dependence on the newly refined metallicity parameter, zeta. We also developed a photometric metallicity parameter, delta((g-r)), based on the g - r and r - z colors of low-mass stars and used it to select stars with similar metallicities. The kinematics of low-mass subdwarfs as a function of color and metallicity were also examined and compared to main-sequence M dwarfs. We find that the SDSS subdwarfs share similar kinematics to the inner halo and thick disk. The color-magnitude relations derived in this analysis will be a powerful tool for identifying and characterizing low-mass metal-poor subdwarfs in future surveys such as Gaia and LSST, making them important and plentiful tracers of the stellar halo.

• 出版日期2013-2