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.