SOAR spectroscopic follow up of TCP J18224935-2408280 -- a classical symbiotic outburst?
ATel #14692; E. Aydi, K. V. Sokolovsky, J. Strader, L. Chomiuk, and A. Kawash (MSU)
on 9 Jun 2021; 17:31 UT
Credential Certification: Elias Aydi (aydielia@msu.edu)
Subjects: Optical, Binary, Cataclysmic Variable, Nova, Star, Transient, Variables
Referred to by ATel #: 14699
We report on spectroscopic follow up of the optical transient TCP J18224935-2408280, which was discovered by Tadashi Kojima, Tsumagoi, Gunma-ken, Japan on 2021-05-19.68 UT, and classified spectroscopically as an outburst in a symbiotic system by Merc et al. (ATel#14691). On 2021-06-09.17, we obtained a low-resolution spectrum using the Goodman spectrograph (Clemens et al. 2004, SPIE, 5492, 331) on the 4.1 m SOAR telescope, covering a wavelength range of 4000-7800 A. The spectrum shows a red continuum and strong emission lines of H I, He I, He II, [O III], consistent with the results of Merc et al. (ATel#14691). In addition we also identify the Bowen blend and relatively weak emission lines of Fe II (42, 48, 49 multiplets). The emission lines are characterized with a FWHM of around 200-250 km/s (corrected for instrumental resolution). The Balmer lines are characterized by a broad base with a FWZI of around 3000 km/s.
The red continuum and the presence of Fe II and [O III] lines in the spectrum argue against a dwarf nova outburst. The ASAS-SN light curve (see below) shows a low amplitude outburst of around 3.3 magnitude, which is still ongoing. Gaia DR2 classifies the potential progenitor as a MIRA semi-regular variable. The Gaia match has average magnitude G = 14.4 and color G_bp - G_rp = 2.5, consistent with a red progenitor. The Gaia parallax is 0.110 +/- 0.024, indicating a distant source (d >= 8 kpc). The overall spectrum and the potentially giant, evolved star in the progenitor system, suggest that the outburst is likely a classical symbiotic outburst, consistent with the conclusions of Merc et al. (ATel#14691). Follow up observations are encouraged in all bands.
The latest ASAS-SN light curve (Kochanek et al. 2017, PASP, 129, 4502): https://asas-sn.osu.edu/sky-patrol/coordinate/82307cf3-43bf-4f62-8ebc-c8d13e37c977
This ATel is based on observations obtained at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministerio da Ciencia, Tecnologia, Inovacoes e Comunicacoes do Brasil (MCTIC/LNA), the U.S. National Science Foundation's National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).
