An Activity-Rotation Relationship and Kinematic Analysis of Nearby M Dwarfs
Abstract
Using spectroscopic observations and photometric light curves of 298 nearby M dwarfs from the MEarth transit survey, we examine the relationships between magnetic activity (quantified by H-alpha emission), rotation period, and stellar age (derived from three-dimensional space velocities). Although we have known for decades that a large fraction of mid-late-type M dwarfs are magnetically active, it was not clear what role rotation played in the magnetic field generation (and subsequent chromospheric heating). Previous attempts to investigate the relationship between magnetic activity and rotation in mid-late-type M dwarfs were hampered by the limited number of M dwarfs with measured rotation periods (and the fact that vsini measurements only probe rapid rotation). However, the photometric data from the MEarth survey allows us to probe a wide range of rotation periods for M dwarf stars (<1-150 days). Over all M spectral types we find that magnetic activity decreases with longer rotation periods. We note the most magnetically active (and hence, most rapidly rotating) stars to be consistent with a kinematically young population, while slow-rotators are less active or inactive and appear to belong to an older, dynamically heated stellar population. We acknowledge MEarth funding from the Packard Fellowship for Science and Engineering, the NSF (AST-0807690 and AST-1109273) and the Boston University UROP Program.
- Publication:
-
American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22115810W