ADDITIONAL MASSIVE BINARIES IN THE CYGNUS OB2 ASSOCIATION

Abstract

We report the discovery and orbital solutions for two new OB binaries in the\nCygnus OB2 Association, MT311 (B2V+B3V) and MT605 (B0.5V+B2.5:V). We also\nidentify the system MT429 as a probable triple system consisting of a tight\neclipsing 2.97 day B3V+B6V pair and a B0V at a projected separation of 138 AU.\nWe further provide the first spectroscopic orbital solutions to the eclipsing,\ndouble-lined, O-star binary MT696 (O9.5V+B1:V), the double-lined, early B\nbinary MT720 (B0-1V+B1-2V), and the double-lined, O-star binary MT771\n(O7V+O9V). These systems exhibit orbital periods between 1.5 days and 12.3\ndays, with the majority having P<6 days. The two new binary discoveries and six\nspectroscopic solutions bring the total number of known massive binaries in the\ncentral region of the Cygnus OB2 Association to 20, with all but two having\nfull orbital solutions.\n