Long-term photometric and low-resolution spectroscopic analysis of five contact binaries

TL;DR

This study conducts a long-term photometric and spectroscopic analysis of five contact binary systems, revealing orbital period changes, mass transfer rates, and spectral emission features, enhancing understanding of their evolutionary processes.

Contribution

It provides new long-term observational data on five contact binaries, including orbital period variations, mass transfer rates, and spectral emission analysis, which were not previously documented in detail.

Findings

Orbital periods of J1013 and J1524 are decreasing.

Mass transfer rates from primary to secondary are quantified.

Spectral analysis shows excess H-alpha emission in some systems.

Abstract

A photometric and spectroscopic investigation is performed on five W Ursae Majoris eclipsing binaries (EWs) J015818.6+260247 (hereinafter as J0158b), J073248.4+405538 (hereinafter as J0732), J101330.8+494846 (hereinafter as J1013), J132439.8+130747 (hereinafter as J1324) and J152450.7+245943 (hereinafter as J1524). The photometric data are collected with the help of the 1.3\,m Devasthal Fast Optical Telescope (DFOT), the 1.04\,m Sampurnanand Telescope (ST) and the TESS space mission. The low-resolution spectra of the 4\,m Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) are used for spectroscopic analysis. The orbital period change of these systems is determined using our and previously available photometric data from different surveys. The orbital period of J1013 and J1524 is changing with a rate of $-2.552(\pm0.249)\times 10^{-7}$ days $yr^{-1}$ and $-6.792(\pm0.952)\times 10^{-8}$ days $yr^{-1}$, respectively, while others do not show any orbital period change. The orbital period change of J1013 and J1524 corresponds to a mass transfer rate of $2.199\times10^{-7} M_{\odot}\,yr^{-1}$ and $6.151\times10^{-8}M_{\odot}\,yr^{-1}$ from the primary to the secondary component in these systems. It is likely that angular momentum loss via magnetic braking may also be responsible for the observed orbital period change in the case of J1524. All systems have a mass-ratio lower than 0.5, except J0158b with a mass-ratio of 0.71. All the systems are shallow type contact binaries. The J0158b and J1524 are A-subtype while others are W-subtype. The $H_{\alpha}$ emission line region is compared with template spectra prepared using two inactive stars with the help of STARMOD program. The J0158, J1324 and J1524 systems show excess emission in the residual spectra after subtraction of the template.