FIVE MORE MASSIVE BINARIES IN THE CYGNUS OB2 ASSOCIATION

Abstract

We present the orbital solutions for four OB spectroscopic binaries, MT145,\nGSC 03161-00815, 2MASS J20294666+4105083, and Schulte 73, and the partial\norbital solution to the B spectroscopic binary, MT372, as part of an ongoing\nstudy to determine the distribution of orbital parameters for massive binaries\nin the Cygnus OB2 Association. MT145 is a new, single-lined, moderately\neccentric (e=0.291+/-0.009) spectroscopic binary with period of 25.140+/-0.008\ndays. GSC 03161-00815 is a slightly eccentric (e=0.10+/-0.01), eclipsing,\ninteracting and double-lined spectroscopic binary with a period of\n4.674+/-0.004 days. 2MASS J20294666+4105083 is a moderately eccentric\n(e=0.273+/-0.002) double-lined spectroscopic binary with a period of\n2.884+/-0.001 days. Schulte 73 is a slightly eccentric (e=0.169+/-0.009),\ndouble-lined spectroscopic binary with a period of 17.28+/-0.03 days and the\nfirst "twin" in our survey with a mass ratio of q=0.99+/-0.02. MT372 is a\nsingle-lined, eclipsing system with a period of 2.228 days and low eccentricity\n(e~0). Of the now 18 known OB binaries in Cyg OB2, 14 have periods and mass\nratios. Emerging evidence also shows that the distribution of log(P) is flat\nand consistent with Oepik's Law.\n