A Target or the Next XCov23 Campaign: KPD 1930+2752

Abstract

AbstractKPD 1930+2752 is a pulsating subdwarf B star with a particularly rich period spectrum, likely due to significant rotational splitting. It is also a short period (~ 2h17m), close binary system (as revealed by the presence of an ellipsoidal variation in the light curve) containing an unseen companion - almost certainly a white dwarf. Radial velocity measurements indicate that the total binary mass exceeds the Chandrasekhar limit. KPD 1930+2752 is therefore the first known (non-X-ray source) candidate for a Type Ia supernova (SNe Ia) progenitor that should explode within an astrophysically interesting timescale (~ 200 Myr) after the two stars merge due to gravitational wave radiation. Additionally, the tidal distortions are indicative of the strong tidal force incurred on the pulsating star by its companion. This will allow us to test the effects such strong tidal forces have on pulsations. Hence, this object presents an outstanding astrophysical interest, and deserves to be observed with the WET network to fully resolve the complex pulsation pattern of the pulsating sdB star, as well as the details of the ellipsoidal modulation. The asteroseismological analysis of the pulsation data obtained with the WET, along with a detailed analysis of the folded, high S/N ellipsoidal variation will lead to strong physical constraints on this particularly interesting stellar object.