Spectroscopic Classification of the Transient TCP J10203579+3103424 = AT 2021bxp = ZTF21aaherhg as a high-amplitude dwarf nova
ATel #14374; Kenta Taguchi, Kohki Uno, Miho Kawabata, Yusuke Tampo, Naoto Kojiguchi, Keisuke Isogai (Kyoto University)
on 7 Feb 2021; 01:39 UT
Credential Certification: Keisuke Isogai (isogai@kusastro.kyoto-u.ac.jp)
Subjects: Optical, Cataclysmic Variable, Transient, Variables
We report on spectra of the transient TCP J10203579+3103424 (= AT 2021bxp = ZTF21aaherhg). We obtained the spectra on 2021-02-06.78 UT by using a fiber-fed integral field spectrograph (KOOLS-IFU; Matsubayashi et al. 2019) mounted on the 3.8-m telescope Seimei (Kurita et al. 2020) at Okayama Observatory of Kyoto University.
As reported to TNS, this transient was discovered by XOSS at R = 13.0 on 2021-02-05.9095 UT. They reported that this object is a possible classical nova or CV based on the large amplitude. Before the discovery report, this object was also detected by ASAS-SN at g = 16.1 on 2021-02-05.21 UT. This object was not detected by ZTF on 2021-02-04.288 (g > 19.1) and on 2021-02-04.351 (r > 19.5). There is a PS1 counterpart of g = 20.8, r = 20.8, i = 20.9, and z = 20.7, meaning that the outburst amplitude is ∼ 8 mag.
A previous outburst was detected in 2007 by CRTS. It was V = 14.3 on 2007-10-15.51. Then the object faded to V = 15.9 on 2007-11-12.45 and to V = 19.0 on 2007-12-16.37. The ASAS-SN Sky Patrol, running from 2012, had not recorded any outbursts.
Our spectra show a blue continuum and Balmer absorption lines. These features suggest that this object is a dwarf nova in outburst, not a classical nova. The large outburst amplitude and the long interval of the outbursts suggest a WZ Sge-type dwarf nova.
Our Spectrum
