Spectroscopic classification of TCP J18200437-1033071 as a dwarf nova
ATel #12656; E. Aydi, J. Strader, L. Chomiuk, A. Kawash, K. V. Sokolovsky, S. Swihart (MSU), and K. Mukai (NASA/GSFC)
on 12 Apr 2019; 14:55 UT
Credential Certification: Elias Aydi (eaydi@saao.ac.za)
Subjects: Optical, Binary, Cataclysmic Variable, Star, Transient
We report on optical spectroscopic observations of the transient TCP J18200437-1033071 which was discovered by Hideo Nishimura (Shizuoka-ken, Japan; CBAT) on 2019-04-08.71 UT at 13.3 mag.
We obtained a 900 s low-resolution spectrum of TCP J18200437-1033071 with the Goodman spectrograph on the SOAR telescope on 2019-04-09.62 UT. The spectrum shows a blue continuum and is dominated by narrow emission lines of H I and He I. We also note the presence of O I and possibly C lines in emission. Hbeta shows a narrow emission on top of a broader absorption feature. The FWHM of the Balmer emission lines is ~ 280 km/s (corrected for instrumental width). We also detect strong but unresolved (due to the low spectral resolution) Na I D interstellar absorption features. This is in good agreement with the high absorption (Av ~ 6) towards the source from the Galactic reddening maps by Schlafly & Finkbeiner (2011, ApJ, 737, 103). The spectrum is characteristic of a dwarf nova in outburst, and it resembles that of WZ Sagittae (Nogami & Iijima 2004, PASJ, 56, S163), particularly due to the possible presence of C emission lines.
Emission line identifications:
H I: 4861 and 6563, 8502, 8545, 8595, 8665, and 8570 A
He I: 4922, 5016, 5876, 6678, 7065, and 7281 A
O I: 7773 and 8446 A
C IV: 5805 A
C II: 7235 A
Unidentified absorption features: 5777 and 7184 A
