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Spectroscopic Classification of the M31 Nova Candidate PNV J00425172+4118142

ATel #5723; S. C. Williams (LJMU), M. J. Darnley (LJMU), M. F. Bode (LJMU), A. W. Shafter (SDSU), J. J. Zhang (YNAO), P. Mazzali (LJMU), E. Pian (INAF)
on 5 Jan 2014; 11:50 UT
Credential Certification: Matt Darnley (M.J.Darnley@ljmu.ac.uk)

Subjects: Optical, Nova

Referred to by ATel #: 5744, 5745

We report spectroscopic and photometric observations of the M31 nova candidate PNV J00425172+4118142 (tentatively designated M31N 2013-12b) discovered on 2013 December 17.696 UT (see ATEL #5671). We obtained a spectrum of the candidate using YFOSC on the 2.4-m telescope of Lijiang Observatory, Yunnan Observatories (YNAO) on 2013 December 21.567 UT, approximately four days after discovery. The spectrum shows strong and broad Balmer emission (FWHM Hα ∼4200 km/s), along with Fe II emission lines, and is consistent with an Fe IIb class nova in M31. Novae belonging to the Fe IIb spectroscopic class are characterized by Fe II emission lines and display broad emission features; whereas members of the Fe II class usually show narrow emission features (Williams, 1992, AJ, 104, 725).

Additionally, we report photometry taken using the IO:O CCD camera on the Liverpool Telescope (LT) and YFOSC on the 2.4-m telescope of Lijiang Observatory:

2013 Dec 18.97 UT: B = 16.497 ± 0.004 (LT)
2013 Dec 18.98 UT: V = 15.916 ± 0.003 (LT)
2013 Dec 21.56 UT: B = 17.76 ± 0.03 (Lijiang)
2013 Dec 21.56 UT: V = 17.40 ± 0.03 (Lijiang)
2013 Dec 21.56 UT: R = 16.84 ± 0.02 (Lijiang)
2013 Dec 21.56 UT: I = 16.61 ± 0.02 (Lijiang)

The nova had brightened significantly between discovery (see ATEL #5671) and our first set of observations about 1.3 days later. Between our two observation epochs (a time of ∼2.6 days) the nova had faded by ∼1.3 and ∼1.5 magnitudes in B and V-band respectively. Therefore, we conclude that the transient appears to be a luminous, fast-fading Fe IIb nova in M31.