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Two bright, variable sources with unusual light curves discovered by ASAS-SN

ATel #10634; T. Jayasinghe, C. S. Kochanek, K. Z. Stanek, P. Vallely, T. W.-S. Holoien, J. V. Shields, T. A. Thompson (OSU), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), Subo Dong (KIAA-PKU)
on 11 Aug 2017; 18:33 UT
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

Subjects: Optical, Variables

Referred to by ATel #: 10677, 10710

As part of an ongoing effort by ASAS-SN project (Shappee et al. 2014; Kochanek et al. 2017) to characterize and catalog all bright variable stars, we have discovered two bright, variable sources with unusual light curves---ASASSN-V J033455.88-053957.9 (mean V~13.0) and ASASSN-V J211014.40-242105.3 (mean V~14.5).

ASASSN-V J033455.88-053957.9 raises slowly in brightness by ~0.5 mag in ~1,800 days (ASAS-SN Sky Patrol light curve; data points in red are likely affected by artifacts and should not be taken into consideration). A spectrum of this source was obtained by the RAVE survey (Kunder et al. 2017) giving values of T_eff=3660 K and log g =5.1 cm/s^2, fairly typical for an early-type M-dwarf. The 2MASS colors for this source (J-H=0.59 and H-Ks=0.10) also correspond to M1/M2 spectral type M-dwarf (West et al. 2011). ASASSN-V J033455.88-053957.9 appears in a number of X-ray catalogs, including the Swift X-ray point source catalogue (Evans et al. 2014). ASAS-SN light curve for ASASSN-V J033455.88-053957.9 is very unusual for an M-dwarf, and we encourage further observations of this source.

ASASSN-V J211014.40-242105.3 (ASAS-SN Sky Patrol light curve) is mostly flat at around V~14.5 mag, with a big drop in brightness of at least ~2 mag, lasting at least 150 days. This source was spectroscopically classified as a cataclysmic variable, with Balmer and HeII 4686A emission lines (Kilkenny et al. 2015). We conclude that ASASSN-V J211014.40-242105.3 is most likely a cataclysmic variable (CV) of the VY Scl type.

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 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).

ASAS-SN Sky Patrol