A photometric variability study of massive stars in Cygnus OB2

TL;DR

This study conducted a 1.5-year photometric variability survey of over 1400 stars in Cygnus OB2, identifying numerous variable massive stars and classifying their variability types using multi-epoch observations.

Contribution

It provides the first extensive variability catalog of massive stars in Cygnus OB2, including new variable detections and detailed light curves for eclipsing binaries.

Findings

Detected 52 confirmed and 19 candidate variable stars.

Classified variables into eclipsing, pulsating, irregular, and Be types.

Derived phased light curves for binaries with periods of 1.3 to 8.5 days.

Abstract

We have conducted a 1.5 year-long variability study of the stars in the Cygnus OB2 association, the region in the northern hemisphere with the highest density of optically visible massive stars. The survey was conducted using four pointings in the Johnson $R$ and $I$ bands with a 35 cm Meade LX200-ACF telescope equipped with a 3.2 Mpixel SBIG ST10-XME CCD camera and includes 300+ epochs in each filter. A total of 1425 objects were observed with limiting magnitudes of 15 in $R$ and 14 in $I$. The photometry was calibrated using reference stars with existing $UBVJHK$ photometry. Bright stars have precisions better than 0.01 magnitudes, allowing us to detect 52 confirmed and 19 candidate variables, many of them massive stars without previous detections as variables. Variables are classified as eclipsing, pulsating, irregular/long period, and Be. We derive the phased light curves for the eclipsing binaries, with periods ranging from 1.3 to 8.5 days.