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

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 ≈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′ × 26′ and observes a region close to the Galactic plane (b = −9.°4) abundant in stars with an average stellar density of ≈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, three candidate eclipsing binaries of type EA, and seven candidate eclipsing binaries of type EW. In assigning preliminary classifications to our detections, we demonstrate the applicability of the Gaia color–magnitude diagram as a powerful classification tool for variable-star studies.

Investigating Stellar Variability in the Open Cluster Region NGC 381

“…On the basis of its period, amplitude, and location on the H-R diagram star 2483 can be classified as a δ Scuti variable star. This star is located within the region assigned for δ Scuti stars on the CMD (Sanghi et al 2021), while it is very close to the constrained region for δ Scuti stars on the CMD given by Gaia Collaboration et al (2019). Therefore, we classified star 2483 as a δ Scuti variable.…”

“…The absolute G versus (G BP − G RP ) color-magnitude diagram (CMD) has been useful in the classification of variable stars. The CMD is particularly important as it provides constrained regions for variable types such as eclipsing binaries, rotational, eruptive, and cataclysmic variables besides pulsating variables (Gaia Collaboration et al 2019;Sanghi et al 2021). Pulsating variables like δ Scuti and γ Dor have very localized clumps on the CMD.…”

“…Pulsating variables like δ Scuti and γ Dor have very localized clumps on the CMD. The separate locations of variables on the CMD help in removing ambiguity due to the similarity in light curves of two different classes of variables (Sanghi et al 2021). We used absolute G magnitudes, G BP , and G RP-band data for 35 variables provided by Anders et al (2019).…”