Friday, June 28, 2013

1306.6330 (J. Sebastian Pineda et al.)

The Sloan digital sky survey data release 7 spectroscopic m dwarf catalog iii: The spatial dependence of magnetic activity in the galaxy    [PDF]

J. Sebastian Pineda, Andrew A. West, John J. Bochanski, Adam J. Burgasser
We analyze the magnetic activity of 59,318 M dwarfs from the Sloan Digital Sky Survey (SDSS) Data Release 7. This analysis explores the spatial distribution of M dwarf activity as a function of both vertical distance from the Galactic plane (Z) and planar distance from the Galactic center (R). We confirm the established trends of decreasing magnetic activity (as measured by H-alpha emission) with increasing distance from the mid-plane of the disk and find evidence for a trend in Galactocentric radius. We measure a non-zero radial gradient in the activity fraction in our analysis of stars with spectral types dM3 and dM4. The activity fraction increases with R and can be explained by a decreasing mean stellar age with increasing distance from the Galactic center.
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