Rotation and differential rotation of active Kepler stars (Reinhold et al.)

Vol. 559
In section 7. Stellar structure and evolution

Rotation and differential rotation of active Kepler stars

by T. Reinhold, A. Reiners, and G. Basri, A&A 560, A4

In a sample of 40 661 active stars surveyed by the Kepler satellite, the authors found 24 124 rotation periods P1 between 0.5 and 45 days, with a mean of 16.3 days. The distribution of stars with 0.5 < B − V < 1.0 and ages derived from angular momentum evolution that are younger than 300 Myr is consistent with a constant star-formation rate; the detection among older stars is incomplete probably because of our active sample selection.

A second period within ±30% of the rotation period was found in 18 619 stars (77.2%). Attributing these two periods to differential rotation, the authors found that for active stars the relative shear increases with rotation period, and slightly decreases with effective temperature.