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Spectroscopic confirmation and photometry of the Fe II nova M31N 2018-01a (AT2018gw)

ATel #11203; S. Fabrika, O. Sholukhova, A. Vinokurov, A. F. Valeev, Yu. Solovyeva (SAO RAS), K. Hornoch (Ondrejov), M. Henze (SDSU), A. W. Shafter (SDSU), S. C. Williams (Lancaster), M. J. Darnley (LJMU)
on 19 Jan 2018; 19:01 UT
Credential Certification: Sergei Fabrika (fabrika@sao.ru)

Subjects: Optical, Nova

We report optical spectroscopic confirmation of the recent M31 nova candidate M31N 2018-01a (AT2018gw) (= PNV J00444425+4142449) (= ATLAS18eat) discovered by Emmanuel Conseil on 2018 Jan. 10.860 UT.

The spectral data were obtained on 2018 Jan. 17.746 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. The photometry of the nova was obtained just before the time of the BTA spectrum with the same device gave B = 18.48 ± 0.06, V = 18.14 ± 0.03, Rc = 17.81 ± 0.05.

The nova M31N 2018-01a shows Balmer emission lines together with all the Fe II lines. In the main lines: H-delta, H-gamma, H-beta, Fe II (4923, 5018, 5169 Å) we observe P Cyg profiles. The blue edge in the absorption components reach to 1870 ± 50 km/s. The hydrogen H-beta line has a width of FWHM = 1060 ± 40 km/s, the H-gamma and H-delta have FWHM = 1150 ± 50 km/s. Three Fe II lines have FWHM = 980 ± 100 km/s. The widths were corrected for spectral resolution. In the case of the hydrogen lines, we find narrow peaks both in absorption and emission components, however for Fe II lines we observe round-shaped profiles in absorption and emission components. We conclude that the M31 nova belongs to the Fe II class.