# Optical Photometric Variable Stars towards Cygnus OB7

## TL;DR

This study presents optical I-band light curves of stars in Cygnus OB7, identifying 31 variable stars, including potential T-Tauri stars, and analyzing their properties and distribution in a star-forming region.

## Contribution

First optical variability survey of stars in Cygnus OB7 with detailed analysis of candidate young stellar objects and their characteristics.

## Key findings

- Detected 31 candidate variable stars, including 14 periodic.
- Identified 4 probable Classical T-Tauri stars.
- Estimated ages of some T-Tauri stars to be around 5 million years.

## Abstract

We present optical $I$-band light curves of the stars towards a star-forming region Cygnus OB7 from 17 nights photometric observations. The light curves are generated from a total of 381 image frames with very good photometric precision. From the light curves of 1900 stars and their periodogram analyses, we detect 31 candidate variables including five previously identified. 14 out of 31 objects are periodic and exhibit the rotation rates in the range of 0.15 to 11.60 days. We characterize those candidate variables using optical/infrared colour-colour and colour-magnitude diagrams. From spectral indices of the candidate variables, it turns out that four are probably Classical T-Tauri stars (CTTSs), rest remain unclassified from present data, they are possibly field stars or diskless pre-main sequence stars towards the region. Based on their location on the various colour-magnitude diagrams, the ages of two T Tauri Stars were estimated to be $\sim$ 5 Myr. The light curves indicate at least five of the periodic variables are eclipsing systems. The spatial distribution of young variable candidates on Planck 857 GHz (350 $\mu$m) and 2MASS $K_s$ images suggest that at least two of the CTTSs are part of the active star-forming cloud Lynds 1003.