SALT spectroscopic follow up of the optical transient Gaia22alz (AT2022bpq)
ATel #15270; J. Brink (SAAO/UCT), E. Aydi (MSU), D. A. H. Buckley (SAAO/UCT), L. Chomiuk (MSU), A. Kawash (MSU), M. Orio (UoW/INAF), J. Mikolajewska (NCAC), K. V. Sokolovsky (MSU), J. Strader (MSU), K. Z. Stanek, C. S. Kochanek, M. R. Smith (OSU), and B. J. Shappee (Univ. of Hawaii)
on 11 Mar 2022; 14:58 UT
Credential Certification: Elias Aydi (aydielia@msu.edu)
Subjects: Optical, Cataclysmic Variable, Nova, Star, Transient, Variables
Referred to by ATel #: 15355
We report on follow up observations of the optical transient Gaia22alz (AT2022bpq), which was discovered by Gaia on 2022-02-04.2 UT at G = 16.87 (https://www.wis-tns.org/object/2022bpq). There is a Gaia EDR3 source matching the transient position, with an average G-magnitude of 18.3.
Photometry from the All Sky Automated Survey for SNe (ASAS-SN; Shappee et al. 2014, ApJ, 788, 48S and Kochanek et al. 2017PASP, 129, 4502) shows that the outburst started around 2022-01-25 and has been rising slowly in brightness since then, reaching a g-magnitude of around 15.2 on 2022-03-09 (https://asas-sn.osu.edu/sky-patrol/coordinate/3471191f-7745-41dc-8576-efc37ceefda0).
On 2020-03-10 we obtained a 300 s spectrum using the Robert Stobie Spectrograph (RSS; Burgh et al. 2003, SPIE, 4841, 1463), mounted on the 11m Southern African Large Telescope as part of the SALT Large Science Program on Transients. The spectrum is dominated by emission lines of Balmer, He II, He I, C IV, and the Bowen blend. The Balmer lines are characterized by a relatively narrow central emission (FWHM ~ 400-500 km/s), with a broad emission base characterized by a FWZI > 5000 km/s. The equivalent width (EW) of He II line at 4686 A is approx 1.5 times that of Hbeta. Based on the spectrophotometric observations, the transient might be an unusual disk instability (dwarf nova) outburst in a cataclysmic variable (CV) system, but further follow up are required to reach a definite classification. The slow rise of the optical light curve resembles the slowly evolving outbursts of the CV systems GK Per, V1017 Sgr, and V1047 Cen.
Follow up observations are encouraged.
Spectrum
