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Spectroscopic confirmation and photometry of the He/N novae M31N 2017-11d and M31N 2017-11e

ATel #10986; S. Fabrika, O. Sholukhova, A. Vinokurov, A. F. Valeev, A. Sarkisyan, (SAO RAS), K. Hornoch (Ondrejov), M. Henze (SDSU), A. W. Shafter (SDSU)
on 18 Nov 2017; 14:55 UT
Credential Certification: Sergei Fabrika (fabrika@sao.ru)

Subjects: Optical, Nova, Transient

Referred to by ATel #: 11031

We report optical spectroscopic confirmation of the two recent M31 nova candidate M31N 2017-11d and 2017-11e. The first nova PNV J00424328+4117152 discovered by Igarashi et al. (ATel #10955), the second discovered by K. Nishiyama and F. Kabashima (PNV J00430419+4115155) and by G. Carey (designated as 2017ifs), and in ATel #10978. The spectral data were obtained on 2017 Nov. 17.67 UT (first nova) and 17.63 UT (second nova) 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 novae obtained near the time of the BTA spectrum with the same device gave B =19.0 ± 0.1, V = 19.5 ± 0.15, Rc = 18.8 ± 0.1 for M31N 2017-11d and B = 17.59 ± 0.07, V = 17.35 ± 0.05, Rc = 16.72 ± 0.06 for M31N 2017-11e.

The optical spectrum of M31N 2017-11d has been previously reported in ATel #10981. The nova strongly dimmed by the time of our spectrum. The H-beta line now has EW = 20 ± 2 Å (FWHM = 3500 ± 300 km/sec), H-gamma line has EW = 15 ± 2 Å (FWHM = 3600 ± 300 km/sec). We also observe NIII, NV, HeI lines, but they are too broad and noisy to measure their properties.

The second nova M31N 2017-11e is bright and has good S/N. The H-beta line has EW = 150 Å (FWHM = 5550 km/sec), the H-gamma line has EW = 73 Å (FWHM = 4980 km/sec), the H-delta line has EW = 50 Å (FWHM = 4170 km/sec), the HeI line 4471 Å has EW = 22 Å (FWHM = 4600 km/sec), and the HeI line 5015 Å has EW = 28 Å (FWHM = 4950 km/sec). The two HeI lines have a second peak on the blue side, making it difficult to measure the FWHM. The widths were corrected for spectral resolution.

Based on their spectral characteristics, we suggest that these two novae belong to the He/N class.