WIYN open cluster study. XXXVI. Spectroscopic binary orbits in NGC 188

Abstract

We present 98 spectroscopic binary orbits resulting from our ongoing radial velocity survey of the old (7 Gyr) open cluster NGC 188. All but 13 are high-probability cluster members based on both radial velocity and proper motion membership analyses. Fifteen of these member binaries are double lined. Our stellar sample spans a magnitude range of 10.8 ≤V≤ 16.5 (1.14-0.92 M ⊙) and extends spatially to 17 pc (∼13 core radii). All of our binary orbits have periods ranging from a few days to on the order of 103 days, and thus are hard binaries that dynamically power the cluster. For each binary, we present the orbital solutions and place constraints on the component masses. Additionally, we discuss a few binaries of note from our sample, identifying a likely blue straggler-blue straggler binary system (7782), a double-lined binary with a secondary star which is underluminous for its mass (5080), two potential eclipsing binaries (4705 and 5762), and two binaries which are likely members of a quadruple system (5015a and 5015b). © 2009. The American Astronomical Society. All rights reserved.