Optical Photometric Variable Stars towards the Galactic \hii region NGC 2282
Abstract
We report here CCD -band time-series photometry of a young (25 Myr) cluster NGC 2282 to identify and understand the variability of pre-main-sequence (PMS) stars. The -band photometry, down to 20.5 mag, enables us to probe the variability towards the lower mass end ( 0.1 M) of the PMS stars. From the light curves of 1627 stars, we identified 62 new photometric variable candidates. Their association with the region was established from H emission and infrared (IR) excess. Among 62 variables, 30 young variables exhibit H emission, near-IR (NIR)/mid-IR (MIR) excess or both, and they are candidate members of the cluster. Out of 62 variables, 41 are periodic variables with the rotation rate ranging from 0.2 to 7 days. The period distribution exhibits a median period at 1-day as in many young clusters (e.g., NGC~2264, ONC, etc.), but it follows a uni-modal distribution unlike others having bimodality with the slow rotators peaking at 68 days. To investigate the rotation-disk and variability-disk connection, we derived NIR excess from (IK) and MIR excess from [3.6][4.5] m data. No conclusive evidence of slow rotation with the presence of disks around stars and fast rotation for diskless stars is obtained from our periodic variables. A clear increasing trend of the variability amplitude with the IR excess is found for all variables.
Keywords
Cite
@article{arxiv.1802.02303,
title = {Optical Photometric Variable Stars towards the Galactic \hii region NGC 2282},
author = {Somnath Dutta and Soumen Mondal and Santosh Joshi and Jessy Jose and Ramkrishna Das and Supriyo Ghosh},
journal= {arXiv preprint arXiv:1802.02303},
year = {2018}
}