ASAS-SN Discovery of an Unusual, Rapidly Fading Star
ATel #13346; Z. Way, K. Z. Stanek, C. S. Kochanek, T. Jayasinghe, P. Vallely, C. Basinger, 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), M. Stritzinger (Aarhus)
on 11 Dec 2019; 21:05 UT
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)
Subjects: Optical, Star, Variables
During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014, Kochanek et al. 2017), using data from the quadruple 14-cm "Brutus", "Cassius", "Payne-Gaposchkin", "Leavitt", and "Paczynski" telescopes, we identified a stellar source undergoing an unusual dimming episode. The source ASASSN-V J060000.76-310027.83 (position from Gaia DR2, source_id=2891196718939580672, d=156 pc, L=0.14 L_sun, T_eff=4270 K) was first observed by ASAS-SN on UT 2013-10-24. Presently, ASASSN-V J060000.76-310027.83 has more than ~2790 data points.
The source ASASSN-V J060000.76-310027.83 has a quiescent mean magnitude of g~14.2 (V~13.6). The latest ASAS-SN photometry shows that ASASSN-V J060000.76-310027.83 gradually faded from g~14.2 on UT 2019-10-25.35, to g~15.1 on 2019-12-11.16. Over the previous ~2230 days the source shows no previous variability in its ASAS-SN g or V-band data. There are no matches in Vizier or AAVSO to a known variable star and the star is not variable in CRTS or ASAS data, going back to 2001. With M_V=7.6 mag it cannot be a classical R Cor Bor star, and in general, its behavior does not match with any common type of stellar variability.
Follow-up observations of this very unusual object are strongly encouraged.
We 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 grants AST-1515927 and AST-1908570, 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). For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.
