We analyze 221 eclipsing binaries ( EBs ) in the Large Magellanic Cloud with B-type main-sequence ( MS ) primaries ( M _ { 1 } \approx 4 - 14 M _ { \odot } ) and orbital periods P = 20 - 50 days that were photometrically monitored by the Optical Gravitational Lensing Experiment .
We utilize our three-stage automated pipeline to ( 1 ) classify all 221 EBs , ( 2 ) fit physical models to the light curves of 130 detached well-defined EBs from which unique parameters can be determined , and ( 3 ) recover the intrinsic binary statistics by correcting for selection effects .
We uncover two statistically significant trends with age .
First , younger EBs tend to reside in dustier environments with larger photometric extinctions , an empirical relation that can be implemented when modeling stellar populations .
Second , younger EBs generally have large eccentricities .
This demonstrates that massive binaries at moderate orbital periods are born with a Maxwellian “ thermal ” orbital velocity distribution , which indicates they formed via dynamical interactions .
In addition , the age-eccentricity anticorrelation provides a direct constraint for tidal evolution in highly eccentric binaries containing hot MS stars with radiative envelopes .
The intrinsic fraction of B-type MS stars with stellar companions q = M _ { 2 } / M _ { 1 } > 0.2 and orbital periods P = 20 - 50 days is ( 7 \pm 2 ) % .
We find early-type binaries at P = 20 - 50 days are weighted significantly toward small mass ratios q \approx 0.2 - 0.3 , which is different than the results from previous observations of closer binaries with P < 20 days .
This indicates that early-type binaries at slightly wider orbital separations have experienced substantially less competitive accretion and coevolution during their formation in the circumbinary disk .