The Photometric Study of Six W UMa Systems and Investigation of the Mass–Radius Relations for Contact Binary Stars

Abstract

We present the photometric analysis of six short-period systems (EI Oct, V336 TrA, NX Boo, V356 Boo, PS Boo, and V2282 Cyg). This is the first photometric analysis of these systems except for V336 TrA. Observations were conducted for 27 nights at three observatories in the northern and southern hemispheres. We calculated a new ephemeris for each of the systems using our minimum times and additional literature. The Markov Chain Monte Carlo (MCMC) approach was used to determine the eclipse timing variation trends of the systems. We found a likely orbital growth for V336 TrA and PS Boo; four other systems show a linear trend in orbital period changes, which is most likely due to the accumulation of measurement errors in their linear ephemeris parameters. The light curve analysis was performed using the Physics of Eclipsing Binaries (PHOEBE) 2.3.59 version code with the MCMC approach. The absolute parameters of the systems were calculated by using the Gaia Early Data Release 3 (EDR3) parallax. The positions of the systems were also depicted on the Hertzsprung–Russell (H-R) and log J 0 – log M diagrams. According to a sample, we were able to present relations for the mass–radius (M–R) relationships of contact binary systems. There is also a strong relationship between the mass ratio and the radius ratio in the W UMa systems for which we also provided a new relation. We compared the M–R updated relationships in this study with seven systems in other studies obtained using the spectroscopic method. In addition, we estimated some of the absolute parameters for 1734 EW systems, based on the new relationships.

The First Multiband Photometric Light Curve Solutions of the V Gru Binary System from the Southern Hemisphere

“…We used the MCMC approach to obtain a new ephemeris for the system (e,g. Poro et al 2022). We find the revised period to be 0.483469038 days for the V Gru system.…”

“…Photometric light curve analysis of the V Gru system was performed by Python Version 2.4.7 of PHOEBE (Prša & Zwitter 2005, Conroy et al 2020, Poro et al 2022. We first found a good fit based on all of the initial inputs and the appearance of the light curves.…”

“…This study provided a total of 196 mid-eclipse timings for V Gru, including 184 extracted from TESS data, listed in Tables 2 and the appendix table. We used the MCMC approach to obtain a new ephemeris for the system (e.g., Poro et al 2022). We find the revised period to be 0.483469038 days for the V Gru system.…”

Global Parameters of Eight W UMa-type Binary Systems

“…It can be seen in Figure 2 that all q-search curves have a clear minimum sum of the squared residuals, and the mass ratios have been obtained with proper accuracy. According to the Poro et al (2022a) study the mass ratio has a significant relationship with the radius ratio in contact binary systems. Figure 8 shows how the values obtained from the light curve solutions and the absolute parameters for q and R ratio lie along the theoretical fit.…”

Light Curve Analysis of the AP Dor Binary System using Ground-based and TESS Observations

“…Light curve analysis of the AP Dor binary system was carried out using the PHysics Of Eclipsing BinariEs (PHOEBE) 2.4.9 version and the MCMC approach (Prša & Zwitter 2005;Conroy et al 2020;Poro et al 2022a). We selected contact mode for the light curve solutions based on how the light curve appeared and the system's short orbital period.…”