Optical Spectroscopy of Transient TCP J18490521-1902054: A classical nova of the Fe II class in an early outburst phase
ATel #14487; Mudit K. Srivastava, Vipin Kumar, Dipankar P K Banerjee, Vishal Joshi, Physical Research Laboratory, Ahmedabad, India
on 27 Mar 2021; 08:02 UT
Credential Certification: Dipankar P.K. Banerjee (dpkb12345@gmail.com)
Subjects: Infra-Red, Nova
Referred to by ATel #: 14637
We report optical spectroscopy of the transient TCP J18490521-1902054 reported by Hideo Nishimura, Kakegawa, Shizuoka-ken on
2021 03 25.761 UT and by Yuji Nakamura, Kameyama, Mie, Japan, on 2021 03
25.8034 UT with 11.2 mag. On 2021 03 26.5038 UT, magnitudes of V = 10.869 and B =
11.177 were reported by Robert Fidrich, Budapest, Hungary
(http://www.cbat.eps.harvard.edu/unconf/followups/J18490521-1902054.html).
Archival records show the transient was likely first detected by the All-Sky Automated Survey for
Supernovae (ASAS-SN) as ASASSN-21eh ( g=11.9 on 2021-03-25.2953UT; http://www.astronomy.ohio-state.edu/~assassin/transients.html )
We recorded optical spectra of TCP J18490521-1902054 on 2021-03-26.98 UT
using the Mt. Abu Faint Object Spectrograph and Camera - Pathfinder
(MFOSC-P) instrument (Srivastava at al. 2018, Proc. SPIE, 10702-163) on the PRL 1.2m Telescope at Mt. Abu. The spectra were recorded in three spectroscopic modes viz. (1) a low resolution mode with R ~ 500- 600 covering the 4600-8900A in two settings of the grating; (2.) R~1000 mode
covering 4850-6600A and (3.) a R = 2000 mode covering ~ 6100-7100A
centered around H-alpha. H-beta and H-alpha emission are seen with
prominent P Cygni profiles. In addition, O I 7773 and O I 8446 emission are
also seen in emission with P Cygni profiles. Most of the other lines are seen prominently in absorption with weak emission components.
The separations between the P Cygni emission peaks to absorption minima are 1360, 1460 and 1270 km/s for the H-Beta, H-Alpha and O I 7773A lines respectively (profiles not deconvolved for instrumental broadening). The observed FWHM of the emission component of H-alpha is ~30 Angstrom (~1370 km/s) for the R = 1000 spectrum. All Fe II multiplets, associated wi th the Fe II class of novae, with prominent P Cygni profiles are seen. Thus, the spectra seems to be of a classical nova of the Fe II class, caught early in its outburst. From the AAVSO light curve it appears the object may not yet have reached its maximum brightness. Further, the observed E(B-V) value of approximately 0.3 suggests a modest reddening to the nova.
