Identifying Periodic Variable Stars and Eclipsing Binary Systems with Long-Term Las Cumbres Observatory Photometric Monitoring of ZTF J0139+5245

TL;DR

This study utilized long-term photometric monitoring with Las Cumbres Observatory to identify and classify variable stars and eclipsing binaries near the Galactic plane, discovering 38 new variables and demonstrating the effectiveness of Gaia CMDs for classification.

Contribution

The paper introduces a new method combining LCO photometry with Gaia CMDs to efficiently detect and classify variable stars and eclipsing binaries in a dense stellar field.

Findings

Discovered 38 variable sources, 27 newly classified.

Identified 28 candidate BY Draconis variables.

Detected 10 candidate eclipsing binaries (3 EA, 7 EW).

Abstract

We present the results of our search for variable stars using the long-term Las Cumbres Observatory (LCO) monitoring of white dwarf ZTF J0139+5245 with the two 1.0-m telescope nodes located at McDonald Observatory using the Sinistro imaging instrument. In this search, we find 38 variable sources, of which 27 are newly discovered or newly classified (71%) based on comparisons with previously published catalogs, thereby increasing the number of detections in the field-of-view under consideration by a factor of $\approx$ 2.5. We find that the improved photometric precision per-exposure due to longer exposure time for LCO images combined with the greater time-sampling of LCO photometry enables us to increase the total number of detections in this field-of-view. Each LCO image covers a field-of-view of $26' \times 26'$ and observes a region close to the Galactic plane ($b = -9.4^\circ$) abundant in stars with an average stellar density of $\approx 8$ arcmin$^{-2}$. We perform aperture photometry and Fourier analysis on over 2000 stars across 1560 LCO images spanning 537 days to find 28 candidate BY Draconis variables, 3 candidate eclipsing binaries of type EA, and 7 candidate eclipsing binaries of type EW. In assigning preliminary classifications to our detections, we demonstrate the applicability of the Gaia color-magnitude diagram (CMD) as a powerful classification tool for variable star studies.