SuperWASP discovery and SALT confirmation of a semi-detached eclipsing binary that contains a delta Scuti star

TL;DR

This paper reports the discovery of a semi-detached eclipsing binary system containing a delta Scuti pulsator, confirmed through photometry and spectroscopy, with detailed stellar parameters and pulsation mode analysis.

Contribution

First identification and detailed characterization of a bright delta Scuti star in a semi-detached eclipsing binary using SuperWASP and SALT data.

Findings

Confirmed binary nature with radial velocity spectroscopy.

Determined stellar masses and radii through modeling.

Identified pulsation mode as likely first overtone radial.

Abstract

We searched the SuperWASP archive for objects displaying multiply periodic photometric variations. Specifically we sought evidence for eclipsing binary stars displaying a further non-harmonically related signal in their power spectra. The object SWASP J050634.16-353648.4 is identified as a relatively bright (V ~ 11.5) semi-detached eclipsing binary with a 5.104 d orbital period that displays coherent pulsations with a semi-amplitude of 65 mmag at a frequency of 13.45 per day. Follow-up radial velocity spectroscopy with the Southern African Large Telescope confirmed the binary nature of the system. Using the phoebe code to model the radial velocity curve with the SuperWASP photometry allowed parameters of both stellar components to be determined. This yielded a primary (pulsating) star with a mass of 1.73 +/- 0.11 solar mass and a radius of 2.41 +/- 0.06 solar radii plus a Roche-lobe filling secondary star with a mass of 0.41 +/- 0.03 solar mass and a radius of 4.21 +/- 0.11 solar radii. 1SWASP J050634.16-353648.4 is therefore a bright delta Sct pulsator in a semi-detached eclipsing binary with one of the largest pulsation amplitudes of any such system known. The pulsation constant indicates that the mode is likely a first overtone radial pulsation.