STELLAR RADIAL VELOCITIES IN THE OLD OPEN CLUSTER M67 (NGC 2682) I. MEMBERSHIPS, BINARIES, AND KINEMATICS ∗ Aaron M. Geller†,‡ Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics & Astronomy, Northwestern University, Evanston, IL 60201, USA, Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637, USA;
[email protected] David W. Latham Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA;
[email protected] Robert D. Mathieu† Department of Astronomy, University of Wisconsin - Madison, WI 53706, USA;
[email protected] ABSTRACT We present results from 13776 radial-velocity measurements of 1278 candidate members of the old (4 Gyr) open cluster M67 (NGC 2682). The measurements are the results of a long-term survey that includes data from seven telescopes with observations for some stars spanning over 40 years. For narrow-lined stars, radial velocities are measured with precisions ranging from about 0.1 to 0.8 km s−1. The combined stellar sample reaches from the brightest giants in the cluster down to about 4 mag- nitudes below the main-sequence turnoff (V = 16.5), covering a mass range of about 1.34 M⊙ to 0.76 M⊙. Spatially, the sample extends to a radus of 30 arcminutes (7.4 pc in projection at a distant of 850 pc or 6-7 core radii). We find M67 to have a mean radial velocity of +33.64 km s−1 (with an internal precision of ±0.03 km s−1) well separated from the mean velocity of the field.