期刊
ASTROPHYSICAL JOURNAL
卷 834, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.3847/1538-4357/834/1/85
关键词
stars: activity; stars: low-mass; stars: rotation
资金
- NSF Astronomy and Astrophysics Postdoctoral Fellowship [AST-1602597]
- National Science Foundation (Alan T. Waterman Award) [AST-0807690, AST-1109468, AST-1004488]
- David and Lucile Packard Foundation Fellowship for Science and Engineering
- John Templeton Foundation
- NASA
- NSF
- NASA Astrophysics Data System (ADS)
- SIMBAD database
- VizieR catalog access tool, at CDS, Strasbourg, France
- Division Of Astronomical Sciences [1616624] Funding Source: National Science Foundation
The high-energy emission from low-mass stars is mediated by the magnetic dynamo. Although the mechanisms by which fully convective stars generate large-scale magnetic fields are not well understood, it is clear that, as for solar-type stars, stellar rotation plays a pivotal role. We present 270 new optical spectra of low-mass stars in the Solar Neighborhood. Combining our observations with those from the literature, our sample comprises 2202 measurements or non-detections of H alpha emission in nearby M dwarfs. This includes 466 with photometric rotation periods. Stars with masses between 0.1 and 0.6 M-circle plus are well-represented in our sample, with fast and slow rotators of all masses. We observe a threshold in the mass-period plane that separates active and inactive M dwarfs. The threshold coincides with the fast-period edge of the slowly rotating population, at approximately the rotation period at which an era of rapid rotational evolution appears to cease. The well-defined active/inactive boundary indicates that Ha activity is a useful diagnostic for stellar rotation period, e.g., for target selection for exoplanet surveys, and we present a mass-period relation for inactive M dwarfs. We also find a significant, moderate correlation between L-H alpha/L-bol and variability amplitude: more active stars display higher levels of photometric variability. Consistent with previous work, our data show that rapid rotators maintain a saturated value of L-H alpha/L-bo. Our data also show a clear power-law decay in L-H alpha/L-bo with Rossby number for slow rotators, with an index of -1.7 +/- .0.1.
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