Presentation #438.07 in the session “Stellar Binaries 2”.
During the ongoing All-Sky Automated Survey for Supernovae (ASAS-SN) we discovered an unusual transient where the quiescent, stellar source dropped 0.88 mag in the g-band. This is part of a recent effort by ASAS-SN to look for objects with large drops in flux, much like Tabby’s star. The TESS light curve revealed that the star is a highly eccentric eclipsing binary (e=0.811, Porb=18.46 days) with significant rotational variability. Both stars are chromospherically active, allowing us to determine their rotational periods of P1=1.52 days and P2=1.79 days, respectively. A LBT/MODS spectrum shows that the primary is a G9 dwarf with a temperature Teff=4926 K and Gaia reports a distance and luminosity (315 pc, 0.603 Lsun). We then fit the TESS light curve with an analytical model to determine the complete system geometry.