A New Catalog of Variable Stars in the Field of the Open Cluster M37

TL;DR

This paper presents a comprehensive re-analysis of stellar variability in M37, discovering 2306 variable stars using new photometry and analysis methods, significantly expanding the known variable star catalog in this field.

Contribution

The study introduces a new photometry and de-trending method, along with modified periodogram and change-point analysis tools, enabling the detection of a broader range of stellar variability.

Findings

Identified 2306 variable stars, a 60% increase over previous catalogs.

Discovered 61 eclipsing binaries, 92 multiperiodic, 132 aperiodic, and 436 flare stars.

Corrected previous false positives, improving catalog accuracy.

Abstract

We present a comprehensive re-analysis of stellar photometric variability in the field of the open cluster M37 following the application of a new photometry and de-trending method to MMT/Megacam image archive. This new analysis allows a rare opportunity to explore photometric variability over a broad range of time-scales, from minutes to a month. The intent of this work is to examine the entire sample of over 30,000 objects for periodic, aperiodic, and sporadic behaviors in their light curves. We show a modified version of the fast $\chi^{2}$ periodogram algorithm (F$\chi^{2}$) and change-point analysis (CPA) as tools for detecting and assessing the significance of periodic and non-periodic variations. The benefits of our new photometry and analysis methods are evident. A total of 2306 stars exhibit convincing variations that are induced by flares, pulsations, eclipses, starspots, and unknown causes in some cases. This represents a 60% increase in the number of variables known in this field. Moreover, 30 of the previously identified variables are found to be false positives resulting from time-dependent systematic effects. New catalog includes 61 eclipsing binary systems, 92 multiperiodic variable stars, 132 aperiodic variables, and 436 flare stars, as well as several hundreds of rotating variables. Based on extended and improved catalog of variables, we investigate the basic properties (e.g., period, amplitude, type) of all variables. The catalog can be accessed through the web interface (http://stardb.yonsei.ac.kr/).