Sounding open clusters: Asteroseismic constraints from kepler on the properties of NGC6791 and NGC6819

WOS: 000287194100010
We present initial results on some of the properties of open clusters NGC 6791 and NGC 6819 derived from asteroseismic data obtained by NASA's Kepler mission. In addition to estimating the mass, radius, and log g of stars on the red giant branch (RGB) of these clusters, we estimate the distance to the clusters and their ages. Our model-independent estimate of the distance modulus of NGC 6791 is (m - M)(0) = 13.11 +/- 0.06. We find (m - M)(0) = 11.85 +/- 0.05 for NGC 6819. The average mass of stars on the RGB of NGC 6791 is 1.20 +/- 0.01 M-circle dot, while that of NGC 6819 is 1.68 +/- 0.03 M-circle dot. It should be noted that we do not have data that cover the entire RGB and the actual mass will be somewhat lower. We have determined model-dependent estimates of ages of these clusters. We find ages between 6.8 and 8.6 Gyr for NGC 6791, however, most sets of models give ages around 7 Gyr. We obtain ages between 2 and 2.4 Gyr for NGC 6819.
NASA's Science Mission Directorate; Science and Technology Facilities CouncilScience & Technology Facilities Council (STFC) [ST/F002041/1]
Funding for the Kepler mission is provided by NASA's Science Mission Directorate. The authors wish to thank the entire Kepler team, without whom these results would not be possible. We also thank all funding councils and agencies that have supported the activities of Working Group 2 of the Kepler Asteroseismic Science Consortium.