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Spectroscopic confirmation and photometry of the nova candidate M31N 2016-12d

ATel #9941; S. Fabrika, O. Sholukhova, A. Vinokurov, A. F. Valeev, A. Sarkisyan, (SAO RAS), K. Hornoch (Ondrejov), M. Henze (CSIC-IEEC), A. W. Shafter (SDSU)
on 5 Jan 2017; 11:42 UT
Credential Certification: Sergei Fabrika (fabrika@sao.ru)

Subjects: Optical, Nova, Transient

Referred to by ATel #: 10003

We report optical spectroscopic confirmation of the recent M31 nova candidate M31N 2016-12d (= AT2016jbg), TNS discovered 2016/12/25.510 by Wei Gao and Xing Gao, announced in ATel #9915. The spectral data were obtained on 2016 Jan. 2.87 UT using the Russian BTA telescope equipped with the SCORPIO spectrograph. The spectrum was taken with a resolution of 5.3 Å in the 4050 - 5810 Å range.

Photometry of the nova obtained shortly around to the BTA spectrum with the same device gave B = 16.7 ± 0.1, V = 16.42 ± 0.07, Rc = 16.09 ± 0.03.

The nova shows Balmer emission lines, numerous and extremely strong Fe II lines. The hydrogen H-beta line has a width FWHM = 2750 km/sec. The widths were corrected for spectral resolution. The line is double-peaked with peak velocities of -210 km/sec and 600 km/sec. Other hydrogen lines (H-delta, H-gamma) have third bluer component. In Fe II lines (5018 Å) we observe three strong components at -1350, -40 and 600 km/sec. The total width of this non-blended line (FWZM) is about 5400 km/sec. We have also clear detected N II line 5679 Å with FWHM = 1800 km/sec. In spite of that detection we conclude that this M31 nova belongs to the Fe II class. Given that the line widths are significantly broader than typically seen in Fe II novae, the object may be better described as an Fe IIb nova as defined in Williams (1992).