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Spectroscopic Classification of M31N 2017-09b and M31N 2017-09c

ATel #10754; S. C. Williams (Lancaster), M. J. Darnley (LJMU)
on 15 Sep 2017; 23:24 UT
Credential Certification: Steven Williams (scw@astro.ljmu.ac.uk)

Subjects: Optical, Nova, Transient

We obtained a spectrum of classical nova candidate M31N 2017-09b (PNV J00425895+4126279, AT2017gqw; see CBAT TOCP, TNS, ATel #10726) with the SPRAT spectrograph (resolution R ~ 350; Piascik et al. 2014) on the 2-m Liverpool Telescope (Steele et al. 2004) on 2017 Sep 15.13 UT. The spectrum of M31N 2017-09b shows strong Balmer emission lines (Hα, Hβ, Hγ) and we measure the FWHM of Hα to be ~1700 km/s. We identify Fe II emission lines, including the 42, 48, 49 and 74 multiplets, along with Na I D (which shows a P-Cygni profile) and O I 7774 Å.

We also obtained a spectrum of nova candidate M31N 2017-09c (AT2017gsc; see TNS) with SPRAT on 2017 Sep 15.11 UT. This spectrum shows the Balmer series and the Fe II 27, 28, 37, 38, 42, 48 and 49 multiplets with P-Cygni profiles. In addition, Fe II 74 multiplet, Na I D and Si II 6347/6371 Å features are seen mainly in absorption.

These spectra confirm both M31N 2017-09b and M31N 2017-09c are classical novae in M31 and members of the Fe II spectroscopic class.