ASASSN-21qj: A Rapidly Fading, Sun-Like Star
ATel #14879; M. Rizzo Smith, T. Jayasinghe, K. Z. Stanek, C. S. Kochanek, D. M. Rowan, C. Christy, 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 27 Aug 2021; 17:42 UT
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)
Subjects: Optical, Variables
Referred to by ATel #: 14900
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 ``Cassius'', ``Payne-Gaposchkin'', and ``Paczynski'' telescopes, we identified a stellar source undergoing a deep dimming episode. The source ASASSN-21qj (Gaia EDR3 source 5539970601632026752 at RA=08:15:23.2996, DEC=-38:59:23.304, d~556 pc, G=13.4 mag, BP-RP=0.8 mag) is classified as a Sun-like star in the Gaia DR catalog (R=1.03 R_Sun; L=1.1 L_Sun). It was first observed by ASAS-SN on UT 2012-02-09. Presently, ASASSN-21qj has more than ~2800 data points.
ASASSN-21qj has a quiescent mean magnitude of g~13.8 (V~13.4). The latest ASAS-SN photometry shows that ASASSN-21qj was at g~14.2 before becoming Sun constrained on UT 2021-06-29. When the star was again observable on UT 2021-08-26, it had dimmed significantly to g~15.3. As of UT 2021-08-27 ASASSN-21qj is at g~16.0 and appears to still be fading. There were no similar episodes over the previous ~2000 days spanned by the full ASAS-SN light curve.
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 grants GBMF5490 and GBMF10501 to the Ohio State University, NSF grant 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).
