Additional Massive Binaries in the Cygnus OB2 Association

TL;DR

This paper reports the discovery of new massive binary systems and provides orbital solutions for several binaries in the Cygnus OB2 Association, significantly increasing the known population of such systems in this region.

Contribution

It presents the discovery of two new OB binaries and the first spectroscopic orbital solutions for multiple binaries, expanding the catalog of massive binaries in Cygnus OB2.

Findings

Discovered two new OB binaries in Cygnus OB2.

Provided orbital solutions for six binary systems.

Increased the total known massive binaries in Cygnus OB2 to 20.

Abstract

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