An Extreme Amplitude, Massive Heartbeat System in the LMC Characterized Using ASAS-SN and TESS

Abstract

Using ASAS-SN data, we find that the bright ($V\sim 13.5$ mag) variable star MACHO 80.7443.1718 (ASASSN-V J052624.38-684705.6) is the most extreme heartbeat star yet discovered. This massive binary, consisting of at least one early B-type star, has an orbital period of $P_{\mathrm{ASAS}-\mathrm{SN}}=32.83627\pm 0.00846\mathrm{d},$ and is located towards the LH58 OB complex in the LMC. Both the ASAS-SN and TESS light curves show extreme brightness variations of $\sim 40\%$ at periastron and variations of $\sim 10\%$ due to tidally excited oscillations outside periastron. We fit an analytical model of the variability caused by the tidal distortions at pericenter to find orbital parameters of $\ddot{I}‰=-61.4$ deg, $i=44.8$ deg and $e=0.566$. We also present a frequency analysis to identify the pulsation frequencies corresponding to the tidally excited oscillations.

8 pages, 4 figures. Accepted by MNRAS