SALT observations probing the nebular phase of Nova Ret 2020
ATel #14149; Cezary Galan (NCAC PAS, Warsaw, Poland), Joanna Mikolajewska (NCAC PAS)
on 4 Nov 2020; 21:52 UT
Credential Certification: Cezary Galan (cgalan@camk.edu.pl)
We report on high-resolution optical spectroscopy of Nova Ret 2020 (MGAB-V207, YZ Ret; see ATels #13867, #13868, #13874, #14043, #14048, #14067).
The observations were acquired on 2020-10-27.90 UT with the nova of V ~ 9.4mag. We used the High-Resolution Spectrograph (HRS; Crause et al. 2014, Proc. SPIE, 91476) mounted on the 11m Southern African Large Telescope. The 180 s spectrum was taken in the MR mode of HRS with resolving power R~40000 and wavelength coverage of 3700-8800 Å. The data were reduced with the SALT HRS MIDAS pipeline ( Kniazev et al. 2016, MNRAS 459, 3068).
The spectrum reveals a wealth of broad forbidden and permitted emission lines. The strongest features in the spectrum are the [O III] lines. We estimate the relative fluxes of [O III] 5007/Hβ ~ 4.5 and [O III] 4363/Hγ~3.5. We also detect [N II] 5755, [O I] 6300, 6363, [O II] 7320/30 as well as faint [Fe VII] 6087. The [N II] 6548, 6583 lines are blended within much brighter Hα. The Bowen blend is relatively strong and blended with fainter He II 4686 line. There are also weak He I 5876, 6678, and 7065 lines, N II 5680, C III 6206, and C II 7235. All these emission line profiles show practically the same double structure that can be reproduced by two almost identical Gaussian profiles at ~ -710 and ~830 km/s and FWHM~1000 km/s which suggests that the nova shell has by now reached its 'frozen' nebular line structure.
SALT observations will be continued.
Based on observations collected under the SALT program 2019-1-MLT-008. Polish participation in SALT is funded by grant MNiSW DIR/WK/2016/07. We also acknowledge partial support from NCN 2017/27/B/ST9/01940.
