Absolute properties of the binary system BB Pegasi

TL;DR

This study analyzes the binary system BB Peg, revealing its physical parameters, period increase due to mass transfer, and the presence of a third body, contributing detailed observational and orbital insights.

Contribution

It provides new physical parameters, period variation analysis, and third body orbital parameters for BB Peg, based on combined photometric and period data.

Findings

Period increase of 3.0(1) x 10^{-8} days/yr

Mass transfer rate from less to more massive component

Detection of a third body in an eccentric orbit

Abstract

We present a ground based photometry of the low-temperature contact binary BB Peg. We collected all times of mid-eclipses available in literature and combined them with those obtained in this study. Analyses of the data indicate a period increase of 3.0(1) x 10^{-8} days/yr. This period increase of BB Peg can be interpreted in terms of the mass transfer 2.4 x 10^{-8} Ms yr^{-1} from the less massive to the more massive component. The physical parameters have been determined as Mc = 1.42 Ms, Mh = 0.53 Ms, Rc = 1.29 Rs, Rh = 0.83 Rs, Lc = 1.86 Ls, and Lh = 0.94 Ls through simultaneous solution of light and of the radial velocity curves. The orbital parameters of the third body, that orbits the contact system in an eccentric orbit, were obtained from the period variation analysis. The system is compared to the similar binaries in the Hertzsprung-Russell and Mass-Radius diagram.