The stellar rotation–activity relationship in fully convective M dwarfs

By N. Wright, E. Newton, P. Williams, J. Drake, R. Yadav. Monthly notices of the Royal Astronomical Society, 2018

171 citations recorded by the source corpus.

The coronal activity-rotation relationship is considered to be a proxy for the underlying stellar dynamo responsible for magnetic activity in solar and late-type stars. While this has been studied in considerable detail for partly-convective stars that are believed to operate an interface dynamo, it is poorly unconstrained in fully-convective stars that lack the necessary shear layer between radiative core and the convective envelope. We present new X-ray observations of 19 slowly-rotating fully-convective stars with rotation periods from the MEarth Project. We use these to calculate X-ray luminosities (or upper limits for undetected sources) and combine these with existing measurements from \citet{wrig16b}. We confirm the existence of fully-convective stars in the X-ray unsaturated regime and find that these objects follow the same rotation-activity relationship seen for partly-convective stars. We measure the power-law slope of the relationship between Rossby number (the ratio of the rotation period to the convective turnover time) and the fractional X-ray luminosity for X-ray unsaturated fully-convective stars for the first time, and find it to be consistent with that found for partly-convective stars. We discuss this implications of this result for our understanding of stellar magnetic dynamos in fully- and partly-convective stars. Finally, we also use this data to improve empirical estimates of the convective turnover time for fully-convective stars.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/79ef786eaa365ebd2e420be02f3b5b7b9e0eb61d

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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): “This empirical relation, however, is applicable to the flare energy that is emitted in X-rays, whereas in this work we determined the flare energy that is emitted bolometrically (Section 3.7).”