We present the orbital solutions for four OB spectroscopic binaries , MT145 , GSC 03161-00815 , 2MASS J20294666+4105083 , and Schulte 73 , and the partial orbital solution to the B spectroscopic binary , MT372 , as part of an ongoing study to determine the distribution of orbital parameters for massive binaries in the Cygnus OB2 Association .
MT145 is a new , single-lined , moderately eccentric ( e = 0.291 \pm 0.009 ) spectroscopic binary with period of 25.140 \pm 0.008 days .
GSC 03161-00815 is a slightly eccentric ( e = 0.10 \pm 0.01 ) , eclipsing , interacting and double-lined spectroscopic binary with a period of 4.674 \pm 0.004 days .
2MASS J20294666+4105083 is a moderately eccentric ( e = 0.273 \pm 0.002 ) double-lined spectroscopic binary with a period of 2.884 \pm 0.001 days .
Schulte 73 is a slightly eccentric ( e = 0.169 \pm 0.009 ) , double-lined spectroscopic binary with a period of 17.28 \pm 0.03 days and the first “ twin ” in our survey with a mass ratio of q = 0.99 \pm 0.02 .
MT372 is a single-lined , eclipsing system with a period of 2.228 days and low eccentricity ( e \sim 0 ) .
Of the now 18 known OB binaries in Cyg OB2 , 14 have periods and mass ratios .
Emerging evidence also shows that the distribution of log ( P ) is flat and consistent with “ Öpik ’ s Law ” .