Poster Abstracts

Name/Affiliation:  Joerg Weingrill (Leibniz Institute for Astrophysics (AIP))

Title:  IC4756: Cluster Membership and Stellar Rotation

IC4756 is an open cluster in the CoRoT field, and with an age of 800 Myr neatly splits the difference in age between the well-studied Hyades (625 Myr) and NGC 6811 (1 Gyr) clusters. Consequently its rotation periods should lie between those of the Hyades and NGC 6811, independent of an theoretical model, if rotation is indeed a well-defined function of stellar age and mass. Therefore we have performed precision time-series photometry of the IC4756 field for almost 73 days with the CoRoT satellite, and derived 348 main sequence rotation periods in the cluster region. Radial velocity measurements taken with WIYN+Hydra together with multi-color Strömgren photometry using the STELLA robotic telescopes on Tenerife allowed us to identify about 200 cluster members and to compare age-determinations stated by different theories. To date, the cluster member rotation periods indeed lie between those of the Hyades and NGC 6811. The corresponding cluster age is 720 Myrs. We will also present photometry and rotation periods from the Stella Open Cluster Survey (SOCS) from several clusters including NGC 1647, NGC 2281 and M 48.