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Spectroscopy of M31N 1995-11e: Not a Nova, but a Luminous Mira Variable in M31

ATel #1834; A. W. Shafter (SDSU), R. Ciardullo (PSU), M. F. Bode, M. J. Darnley (Liverpool JMU, UK), K. A. Misselt (U. Arizona), K. Nishiyama, F. Kabashima (Miyaki-Argenteus Obs.)
on 7 Nov 2008; 20:38 UT
Credential Certification: Allen W. Shafter (aws@nova.sdsu.edu)

Subjects: Optical, Nova, Transient

Referred to by ATel #: 1851

Recent photometric monitoring of M31 by two of us (K. Nishiyama and F. Kabashima) has revealed that the M31 nova candidate M31N 1995-11e (Nova 1995-08 in Shafter & Irby 2001, ApJ, 563, 749) has re-brightened over the past several months. The object was detected again on 2008 July 6.8 UT at m ~ 18.6 (unfiltered), and has remained detectable up to the present, reaching a peak brightness of m ~ 18 on 2008 September 9 UT.

We obtained a spectrum of the object on 2008 November 3 UT with the Marcario Low-Resolution Spectrograph of the 9.2-m Hobby Eberly Telescope. This spectrum reveals that the object is not a nova: it has strong TiO absorption bands and narrow H&alpha emission (FWHM ~ 350 km/s; EW ~ -7Å RV ~ -40 km/s) superimposed on a very red continuum. This suggests that M31N 1995-11e is a long-period (and very luminous) Mira variable in M31, similar to V14148 D31C (Darnley et al. 2004, MNRAS, 353, 571; Stanek et al. 1999, AJ, 117, 2810). The radial velocity of the H&alpha feature, which is about 260 km/s greater than the mean systemic velocity of M31, is consistent with that expected for a disk object in the North-East (receding) quadrant of the galaxy, ~45' from the nucleus along M31's major axis.