Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample
Abstract
We present a spectroscopic analysis of over 38,000 low-mass stars from the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5). Analysis of this unprecedentedly large sample confirms the previously detected decrease in the fraction of magnetically active stars (as traced by H-alpha emission) as a function of vertical distance from the Galactic Plane. The magnitude and slope of this effect varies as a function of spectral type. Using simple 1-D dynamical models, we demonstrate that the drop in activity fraction can be explained by thin disk dynamical heating and a rapid decrease in magnetic activity. The timescale for this rapid activity decrease changes according to the spectral type. By comparing our data to the simulations, we calibrate the age-activity relation at each M dwarf spectral type. We also present evidence for a possible decrease in the metallicity as a function of height above the Galactic Plane. In addition to our activity analysis, we provide line measurements, molecular band indices, colors, radial velocities, 3-D space motions and mean properties as a function of spectral type for the SDSS DR5 low-mass star sample.
Keywords
Cite
@article{arxiv.0712.1590,
title = {Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample},
author = {Andrew A. West and Suzanne L. Hawley and John J. Bochanski and Kevin R. Covey and I. Neill Reid and Saurav Dhital and Eric J. Hilton and Michael Masuda},
journal= {arXiv preprint arXiv:0712.1590},
year = {2008}
}
Comments
10 pages, 10 figures. Accepted for publication in AJ