A New Look at the YY CrB Binary System

TL;DR

This paper presents a comprehensive analysis of the W UMa binary star YY CrB using TESS data, revealing orbital period changes, potential third body, and evolutionary insights into the system.

Contribution

It introduces a new analysis combining light curve modeling, O-C curve analysis, and third body detection, providing updated orbital parameters and evolutionary implications.

Findings

Calculated orbital period rate of approximately 5.786×10^{-8} day/year.

Estimated mass exchange rate of 2.472×10^{-8} solar masses per year.

Suggested the presence of a third body with a mass of 0.498 solar masses, but unlikely.

Abstract

This study presented a new analysis for the TESS-observed W Ursae Majoris (W UMa) binary star YY Coronea Borealis (YY CrB). The light curve was analyzed by the PHysics Of Eclipsing BinariEs (PHOEBE) Python version together with the Markov chain Monte Carlo (MCMC) method. The light curve solutions required a hot spot and l3. New eclipse times from the TESS observations were extracted, and the O-C curve of primary and secondary minima showed an anti-correlated manner. In order to study the O-C curve of minima, minima times between 1991 and 2023 were collected. This investigation reported a new linear ephemeris and by fitting a quadratic function to the O-C curve of minima, calculated the orbital period rate of \mathop P\limits^.\approx 5.786*{10^{-8}} day/year. Assuming mass conservation, a mass exchange rate of \mathop{{M_2}}\limits^.=2.472*{10^{-8}} calculated from the more massive component to the less massive one. Then, by using the light travel time function, the possible third body was determined in the binary and derived the mass of the third body as 0.498M_Sun with a period of \simeq 7351.018 days. The O-C curve analysis and the quantity of mass indicate that the presence of a third body is unlikely. This binary is expected to evolve into a broken-contact phase and is a good case to support the thermal relaxation oscillation model.