Estimating the absolute parameters of W UMa-type binary stars using Gaia DR3 parallax

Abstract

The accuracy of absolute parameters’ estimation in contact binary systems is important for investigating their evolution and solving some challenges. The Gaia DR3 parallax is one of the methods used for estimating the absolute parameters, in cases where photometric data is the only one that is available. The use of this method includes advantages and limitations that we have described and examined in this study. We selected 48 contact binary systems whose mass ratios were mostly obtained by spectroscopic data, in addition to a number of photometric studies. The target systems were suitable for $A_V$ and the Re-normalized Unit Weight Error (RUWE), and their absolute parameters were calculated based on Gaia DR3 parallax, observational information, orbital period, and light cure solution from the literature and catalogs. The outcomes of OO Aql differed significantly from those reported in the literature. Upon analyzing the system’s light curve with TESS data, we concluded that the stars’ temperatures were the reason for this difference, and utilizing Gaia DR3 parallax provided reasonable results. We displayed the target systems on the Hertzsprung–Russell (HR), $q-L_{ratio}$, $P-M_V$, and $log{M}_{tot}-log{J}_0$ diagrams, and the systems are in good agreement with the theoretical fits. We showed that the estimation of absolute parameters with this method might be acceptable if $\Delta a\left(R_{\odot }\right)$ is less than $\sim 0.1\left(R_{\odot }\right)$. There are open questions regarding the existence of $l_3$ in the light curve analysis and its effect on the estimation of absolute parameters with this method.