ASAS-SN Discovery of a Very Bright, 313-Day Period Detached Eclipsing Binary in the LMC

ATel #11191; T. Jayasinghe, K. Z. Stanek, C. S. Kochanek, J. V. Shields, T. A. Thompson (OSU), B. J. Shappee (Univ. of Hawaii), T. W.-S. Holoien (Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), Subo Dong (KIAA-PKU)
on 17 Jan 2018; 18:54 UT
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

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As part of an ongoing effort by the ASAS-SN project (Shappee et al. 2014; Kochanek et al. 2017; Jayasinghe et al. 2018, in preparation) to characterize and catalog all bright variable stars, we report the discovery of a very bright, long period detached eclipsing binary, most likely a system of two massive stars in the LMC. The source ASASSN-V J054601.74-665924.2 (position from Gaia, g~13.3) was first observed by ASAS-SN on UT 2014-04-29. To date, ASASSN-V J054601.74-665924.2 has more than ~1300 V-band data points and ~180 g-band data points.

The ASAS-SN light curve for ASASSN-V J054601.74-665924.2 clearly shows that this is a detached eclipsing binary with a period P_ecl=313.4364 days (g-band: red points, V-band: blue points). The ASAS-SN light curve shows that the V-band and g-band data agree well (g-V ~0), suggesting that this is an eclipsing binary system composed of two massive stars. The eclipses show some asymmetry, with some similarity to the long period LMC binary OGLE-LMC-ECL-11893 (Dong et al. 2014). When the eclipses are removed from the light curve, we find that this source also shows lower-amplitude intrinsic variability with a period P_intr~15.7 days.

We would like to thank Las Cumbres Observatory and its staff for their continued support of ASAS-SN. ASAS-SN is funded in part by the Gordon and Betty Moore Foundation through grant GBMF5490 to the Ohio State University, NSF grant AST-1515927, the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle Physics (CCAPP) at OSU, and the Chinese Academy of Sciences South America Center for Astronomy (CASSACA).