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arXiv · 0712.1590

Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample

Andrew A. West·Suzanne L. Hawley·John J. Bochanski·Kevin R. Covey·I. Neill Reid·Saurav Dhital·Eric J. Hilton·Michael Masuda
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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.

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Andrew A. West, Suzanne L. Hawley, John J. Bochanski, Kevin R. Covey, I. Neill Reid, Saurav Dhital, Eric J. Hilton, Michael Masuda. 2007-12-10. Constraining the Age-Activity Relation for Cool Stars: The SDSS DR5 Low-Mass Star Spectroscopic Sample. https://doi.org/10.1088/0004-6256%2F135%2F3%2F785

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