EC 01578-1743 is a new hot subdwarf binary discovered by the "wide-seer" Evryscope array on Cerro Tololo. Its light curve reveals an orbital period around six hours and a strong reflection effect, implying a low-mass stellar or substellar companion. Hot subdwarfs are commonly found in these types of post-common envelope binaries, referred to as "HW Vir" systems when they eclipse. Determining the companions' masses and other properties can help shed light on the formation scenarios that lead to hot subdwarf stars. Our analysis of three years of Evryscope photometry finds no primary or secondary eclipses and a ~14% reflection effect, fairly high for HW Vir-type binaries with this orbital period. Spectroscopy was obtained with the CHIRON spectrograph on the CTIO 1.5-m telescope and reveals the radial velocity semi-amplitude of the hot subdwarf to be 86 ± 1 km/s. Here we present our photometric and spectroscopic analyses and argue that the companion is a red dwarf, and one with higher mass than usual for HW Vir-type binaries. This material is based in part upon work supported by the National Science Foundation under Grant No. AST-1812874.
American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019