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Spectroscopic Confirmation of PNV J00424720+4116195 as a (Possibly Recurrent) Nova in M31

ATel #4368; A. W. Shafter (SDSU), K. Hornoch (Astronomical Institute, Ondrejov, Czech Republic), R. Ciardullo (PSU), M. J. Darnley, M. F. Bode (Liverpool JMU)
on 10 Sep 2012; 23:20 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

Subjects: Optical, Nova, Transient

We report spectroscopic observations of the M31 transient PNV J00424720+4116195 (tentatively identified as M31N 2012-09a) discovered on 2012 Sep. 8.770 UT by K. Hornoch and J. Vrastil at R=16.3 +/- 0.15 (ATel #4364). Further photometric observations show that the object is beginning to fade, with R = 16.4, 16.7, 16.7 and 16.9 on Sep. 9.778, 9.856, 10.138 and 10.138 UT, respectively. At our request, a spectrum (410–900 nm) was obtained by S. Odewahn on 2012 Sep. 10.45 UT with the 9.2m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph). The spectrum is characterized by strong Balmer, Fe II (multiplet 42) and He I λ 587.6 nm emission features. The Hα line displays two distinct components: a prominent narrow component (FWHM ~ 1500 km/s) sitting atop a very broad base component (FWZI ~ 10,000 km/s).

These observations confirm that PNV J00424720+4116195 is a nova in M31. The presence of both Fe II and He I emission features, along with the complex structure of the Balmer lines, makes an unambiguous spectroscopic classification difficult. However, it appears that the nova is most likely a member of the broad-lined Fe II or hybrid spectroscopic class. Finally, we note that the position of PNV J00424720+4116195 is nearly coincident (within ~0.5") with those of M31N 1984-07a and M31N 2004-11f. Thus, it appears likely that the object is a recurrent nova as originally suggested by Pietsch et al. (2007, A&A, 465, 375), with PNV J00424720+4116195 representing a third recorded eruption of M31N 1984-07a.

We thank J. Vrastil for assistance with some of the photometric observations. A.W.S. thanks the NSF for support through AST-1009566.

HET Spectra of Local Group Novae