Poster Abstracts

Name/Affiliation:  Benjamin Kidder (University of Redlands)

Title:  Gyrochronology of Low-mass Stars - Age-Rotation-Activity Relations for Young M Dwarfs

We aim to investigate the utility of gyrochronology as a means of determining the ages of low-mass stars. New stellar rotation periods for 48 young (<300 Myr), early-M dwarfs within 25 parsecs were measured using photometric data collected with telescopes at Lowell Observatory during 2012 and 2013. An additional 25 rotation periods for members of the same sample were found in the literature. Ages were derived from Ha and X-ray emission, lithium absorption, surface gravity, and kinematic association of members of known young moving groups (YMGs). We compare rotation periods with the stellar ages with the intention of strengthening and testing age-rotation relationships for young, low-mass stars. We compare ages and rotation periods of our target stars to cluster members and field stars spanning 1 Myr–5 Gyr. Measured rotation periods at every age exhibit a large scatter, with values typically ranging from 0.2 to 15 days. This suggests that gyrochronology for individual field stars will be difficult without a better understanding of the underlying mechanisms that govern angular momentum evolution. Yet, on average, the data still support the predicted trends for spin-up during contraction and spin-down on the main sequence, with the turnover occurring at approximately 150 Myr for early Ms. This suggests that rotation period distributions can be helpful in evaluating the ages of coeval groups of stars. This conclusion has led us to dedicate more observing time to known YMG members, and compare the rotation period distribution at the age of each YMG. We are continuing to measure rotation periods for the low-mass members of 6 YMGs, ages 10-650 Myr to help strengthen the correlation between rotation period distribution and age in coeval clusters. We would like to thank the National Science Foundation for their support through the Research Experience for Undergraduates Grant AST- 1004107.