ASAS-SN Discovery of an Unusual Cataclysmic Variable (ASASSN-20jo)
ATel #13942; Z. Way, D. Desai, K. Z. Stanek, T. Jayasinghe, C. S. Kochanek, 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 13 Aug 2020; 17:48 UT
Credential Certification: Tharindu Jayasinghe (jayasinghearachchilage.1@osu.edu)
Subjects: Optical, Cataclysmic Variable, Star, Variables
Referred to by ATel #: 13943
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" and "Leavitt" telescopes, we identified a stellar source undergoing an unusual series of outbursts. The source ASASSN-20jo (Gaia DR2: RAJ2000=79.24293633, DEJ2000=48.96674100, source_id=213300277925041920, d=834 pc, L = 3.28 L_sun, Teff=5800 K) was first observed by ASAS-SN on UT 2014-12-16 and identified as a transient (CV candidate) on 2020-07-24. The line of sight extinction from the Bayestar19 dust maps (Green et al. 2019) to ASASSN-20jo is A_V~0.64 mag (A_g~0.77 mag). ASASSN-20jo is located towards the anti-Galactic center, and close to the Galactic plane with (l,b)~(160.1737,6.3092). Presently, ASASSN-20jo has more than ~2060 ASAS-SN epochs.
The source ASASSN-20jo has a quiescent mean magnitude of g~13.3 (V~13.1). The latest ASAS-SN photometry shows that ASASSN-20jo had an outburst at g~12.8 on UT 2020-07-24, following a seasonal break in the data. The source then faded to g~13.3 on UT 2020-08-07 and has since brightened to g~12.8 as of 2020-08-12. This source appears to have experienced smaller outbursts previously (on UT 2016-02-01, UT 2018-11-15, UT 2018-12-07, and UT 2020-02-17), as is seen in the complete ASAS-SN V/g-band light curve. It has been classified as a dubious variable by ATLAS (Heinze et.al. 2018). We note that the source is somewhat similar to the novalike variable ASASSN-V J205457.73+515731.9 (T. Jayasinghe et al., ATel #13824) but is more luminous (M_G~2.9 mag). Given the negligible microlensing optical depth at ~800 pc towards the anti-Galactic center, microlensing is unlikely to explain the observed variations in brightness.
Follow-up observations of this interesting 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 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). For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.
