Young Cool Stars Divided on the Issue of Rotation

TL;DR

This study investigates the rotation periods of young cool stars in clusters M35 and M34, revealing two distinct groups with different rotation-mass relationships, and discusses implications for stellar evolution and age estimation methods.

Contribution

It provides new rotation period data for young clusters and identifies a division in stellar rotation behavior based on mass, enhancing understanding of stellar angular momentum evolution.

Findings

Late-type stars in M35 and M34 split into two groups with distinct rotation-mass relations.

Rotation data supports the use of gyrochronology for age estimation.

Plans to extend rotation observations using Kepler beyond current age limits.

Abstract

We present the results of a combination of new stellar rotation periods and extensive information about membership in the young open clusters M35 and M34. The observations show that late-type members of both clusters divide into two distinct groups, each with a different dependence of rotation on mass (color). We discuss these new results in the context of existing rotation data for cool stars in older clusters, with a focus on the dependence of rotation on mass and age. We mention briefly tests of rotation as an "astronomical clock" (gyrochronology), and our plans to use the Kepler space mission to push observations of stellar rotation periods beyond the age of the Hyades and the Sun.