THE KEPLER CLUSTER STUDY: STELLAR ROTATION IN NGC 6811

Abstract

We present rotation periods for 71 single dwarf members of the open cluster\nNGC6811 determined using photometry from NASA's Kepler Mission. The results are\nthe first from The Kepler Cluster Study which combine Kepler's photometry with\nground-based spectroscopy for cluster membership and binarity. The rotation\nperiods delineate a tight sequence in the NGC6811 color-period diagram from ~1\nday at mid-F to ~11 days at early-K spectral type. This result extends to ~1\nGyr similar prior results in the ~600 Myr Hyades and Praesepe clusters,\nsuggesting that rotation periods for cool dwarf stars delineate a well-defined\nsurface in the 3-dimensional space of color (mass), rotation, and age. It\nimplies that reliable ages can be derived for field dwarf stars with measured\ncolors and rotation periods, and it promises to enable further understanding of\nvarious aspects of stellar rotation and activity for cool stars.\n