THE Hα EMISSION OF NEARBY M DWARFS AND ITS RELATION TO STELLAR ROTATION
By E. Newton, J. Irwin, D. Charbonneau, P. Berlind, M. Calkins, Jessica D. Mink. 2016
247 citations recorded by the source corpus.
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 Hα emission in nearby M dwarfs. This includes 466 with photometric rotation periods. Stars with masses between 0.1 and 0.6 M⊙ 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 Hα 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 LHα/Lbol 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 LHα/Lbol. Our data also show a clear power-law decay in LHα/Lbol with Rossby number for slow rotators, with an index of −1.7 ± 0.1.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/04cde809924a485c31224f21cc8233bf6d91e6e7
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In Astronomy and Astrophysics
Citations in the corpus
- Stellar Flares from the First TESS Data Release: Exploring a New Sample of M Dwarfs (2019, background): “Fast rotating M dwarfs (Prot < 10 d) exhibit a saturated level of activity, while for slower rotators, the ratio of X-ray, Hα, and Ca H&K flux to bolometric luminosity declines rapidly (West et al. 2015; Astudillo-Defru et al. 2017; Newton et al. 2017; Wright et al. 2018).”
- The Transit Light Source Effect: False Spectral Features and Incorrect Densities for M-dwarf Transiting Planets (2017, background): “In a study of a compilation of extensive datasets, Newton et al. (2016, 2017) measured photometric semiamplitudes in the range of roughly 0.5–4% (Newton et al. 2017, Fig.”
- The stellar rotation–activity relationship in fully convective M dwarfs (2018, methodology): “21 targets were chosen from the MEarth sample that had rotation periods measured by Irwin et al. (2011) and Newton et al. (2016, 2018).”