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Spectroscopic Observations of PNV J00415824+4124011 and PNV J00423831+4116313

ATel #3778; A. W. Shafter (SDSU), M. J. Darnley, M. F. Bode (Liverpool JMU, UK), R. Ciardullo (PSU)
on 24 Nov 2011; 02:00 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

Subjects: Optical, Nova, Transient

Referred to by ATel #: 4181

We report spectroscopic observations of two recent M31 nova candidates: PNV J00415824+4124011 and PNV J00423831+4116313. The former object was discovered on 2011 Nov. 13.726 by K. Hornoch (and independently by S. Korotkiy and V. Gerke on 2011 Nov. 13.728), with the latter object found on 2011 Nov. 19.704 by K. Hornoch and J. Vrastil.

At our request, spectra of both nova candidates (410–950 nm) were obtained with the Marcario Low-Resolution Spectrograph on the 9.2m Hobby-Eberly Telescope. The spectrum of PNV J00415824+4124011 was obtained by S. Odewahn on 2011 Nov. 18.26 UT (~5 days post discovery), with that of PNV J00423831+4116313 secured by S. Rostopchin on 2011 Nov. 23.27 UT (~4 days post discovery). By the time of our spectroscopic observations both objects had brightened considerably from their discovery magnitudes (m~18).

The spectrum of PNV J00415824+4124011 reveals relatively narrow Balmer emission features (FWHM Hβ ~ 1100 km/s; EW Hβ ~ -1.1 nm), and possibly very weak Fe II features at λ 492.4, 501.8 nm. The spectrum is somewhat unusual in two respects. Firstly, the Hα line appears to have two components: a narrow core component (FWHM ~ 900 km/s) along with a broader base component (HWZI ~ 2200 km/s). Secondly, the continuum flux (in Fλ) begins to turn downward in the blue (shortward of ~570 nm). Overall, the spectrum is consistent with the identification of PNV J00415824+4124011 as a slow nova, most likely of the Fe II spectroscopic class.

The spectrum of PNV J00423831+4116313 reveals narrow (unresolved) Balmer P Cyg features (FWHM Hα emission < 500 km/s; EW Hα emission ~ -0.8 nm) superimposed on a steep blue continuum. In addition, there are numerous Fe II P Cyg features characterized by weak emission and strong absorption components. The spectrum of PNV J00423831+4116313 is consistent with that of a slowly-evolving Fe II nova observed near maximum light.

We thank K. Hornoch for providing finding charts and magnitude estimates for the nova candidates. A.W.S. thanks the NSF for support through AST-1009566.

Spectra of M31 Nova Candidates