Spectroscopic classification AT 2017jdm as a nova, and likely recurrent eruption of M31N 2007-10b
ATel #11088; S. C. Williams (Lancaster), M. J. Darnley (LJMU)
on 24 Dec 2017; 23:46 UT
Credential Certification: Steven Williams (email@example.com)
Subjects: Optical, Nova, Transient
Referred to by ATel #: 11091
We obtained a spectrum of the transient AT 2017jdm (discovered by F. Castellani, R. Belligoli, C. Marangoni and F. Marziali; see TNS) with the SPRAT spectrograph (resolution R ~ 350; Piascik et al. 2014) on the 2-m Liverpool Telescope (Steele et al. 2004) on 2017 Dec 24.86 UT.
The spectrum shows extremely broad Balmer emission, with FWHM of Hα measured at ~ 10,000 km/s. Broad emission lines of He I 5876 Å and N II 5679 Å are also identified. N III 4638 Å is present and there is evidence of P-Cygni absorption profiles accompanying some lines.
As noted by Patrick Schmeer (CBAT TOCP), AT 2017jdm is just 0.3 arcsec away from the position of M31N 2007-10b. The only spectrum of that nova showed the spectrum of a He/N nova, but with line velocities atypically narrow (ATel #1242). If AT 2017jdm is indeed a recurrent eruption of M31N 2007-10b, we may therefore expect significant evolution of the spectrum over the coming days.
In summary, this spectrum confirms AT 2017jdm is a nova eruption in M31, which is likely a recurrent nova outburst of M31N 2007-10b. This nova could evolve quickly and further follow-up is strongly encouraged.