Determination of Light Curve Parameters of Poorly Studied Eclipsing Variables Using Data from Tess and Other Sky Surveys

TL;DR

This study refines the periods and classifications of poorly understood eclipsing variables using data from TESS, sky surveys, and new observations, employing advanced light curve analysis methods to derive stellar parameters.

Contribution

It introduces new period determinations for NSV 575 and NSV 014, reclassifies some variables, and applies innovative light curve approximation techniques with the MAVKA software.

Findings

NSV 575 and NSV 014 periods determined for the first time

NSV 014 likely reclassified as a pulsating star

Refined stellar parameters and eclipse timings using advanced methods

Abstract

A group of poorly studied eclipsing variables (the classification of which is marked as uncertain and/or the period of brightness changes is uncertain) has been studied with the using of the photometric observations of the TESS mission and NSVS, ASAS-SN sky surveys. We also obtained some observations covering the brightness minima of our variables by our group using the telescopes at Astronomical Observatory on Kolonica Saddle (Slovakia) and Observatory and Planetarium in Hlohovec (Slovakia) during the "Variable-2024" astrocamp. The periods and classification were corrected. For NSV 575 and NSV 014 the periods were found for the first time, but it is doubtful that NSV 014 is an eclipsing variable, because there are no eclipses but the asymmetric wave is present, which indicates that the variable star can be re-classified as a low-amplitude pulsating one. Different methods were used for approximation of the light curves and further calculation of stellar system's parameters such as eclipse depths and durations, values of reflection effect and effect of ellipticity of stars. The initial period was estimated using the periodogram based on the trigonometrical polynomial fit of high order (up to 10). For better approximation of the complete eclipsing phase curve, the "New Algol Variable" (NAV) software was used. The methods of "asymptotic parabolas" and "wall-supported asymptotic parabolas" were used for calculation of moments of eclipses, which use only near-eclipse part of the observations instead of a complete curve. These methods were implemented in the software MAVKA among a larger set of features. For the variables NSV 489 and NSV 1884, our moments of eclipses and the ones found in the literature, were used for the O-C curves. For NSV 489, the period was adjusted taking into account the slope of the O-C diagram.