Absolute parameters of the eclipsing binary V821 Cas from UBVRI light curves and radial velocities

TL;DR

This study provides detailed absolute parameters and evolutionary insights for the eclipsing binary V821 Cas through combined photometric and spectroscopic analysis, including mass, radius, temperature, and apsidal motion measurements.

Contribution

The paper presents the first simultaneous analysis of multi-band light curves and radial velocities to determine absolute stellar parameters and apsidal motion for V821 Cas.

Findings

Masses: M1=2.05 M☉, M2=1.63 M☉

Apsidal period: 118 years

Age estimate: 560 million years

Abstract

We present UBVRI photometric measurements and spectroscopic observations of the double-lined eclipsing binary V821 Cas. The radial velocities were obtained by means of the cross-correlation technique. Simultaneous analyses of the multi-band light curves and RVs give the absolute parameters for the stars as: M$_1$=2.05$\pm$0.07 M$_{\odot}$, M$_2$=1.63$\pm$0.06 M$_{\odot}$, R$_1$=2.31$\pm$0.03 R$_{\odot}$, R$_2$=1.39$\pm$0.02 R$_{\odot}$, T$_{eff_1}$=9 400$\pm$400 K, and T$_{eff_2}$=8 600$\pm$400 K. Analysis of the O-C residuals yielded an apsidal motion in the binary at a rate of $\dot{\omega}$=0$^{\degr}$.0149$\pm0^{\degr}$.0023 cycle$^{-1}$, corresponding to an apsidal period of U=118$\pm$19 yr. Subtracting the relativistic contribution we find that $\log k_{2obs}$=-2.590 which is in agreement with the value predicted by theoretical models. Comparison with current stellar evolution models gives an age of $5.6\times10^{8}$ yr for the system.