Spectroscopic Classification of PNV J00444033+4113068 is NOT a nova in M31 but a dwarf nova in the Milky Way Galaxy

ATel #14962; Kenta Taguchi (Kyoto University), Hiroyuki Maehara (National Astronomical Observatory of Japan)
on 10 Oct 2021; 16:27 UT
Credential Certification: Hiroyuki Maehara (hiroyuki.maehara@nao.ac.jp)

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We report spectroscopic observation of PNV J00444033+4113068 = AT 2021aaxp nearby M31 discovered by Koichi Itagaki. We obtained a low-resolution spectrum from 2021-10-09.697 UT to 2021-10-09.718 UT using the fiber-fed integral field spectrograph (KOOLS-IFU; Matsubayashi et al. 2019) mounted on the 3.8 m Seimei telescope (Kurita et al. 2020) at Okayama Observatory of Kyoto University.

As reported to CBAT, this nearby-M31 object was discovered by Koichi Itagaki at 16.5 mag (unfiltered) on 2021-10-09.4579. He further reported that it was brightening: 15.7 mag on 2021-10-09.584, and 15.3 mag on 2021-10-09.806. Also, Dave Balam et al. discovered it identically at 17.77 mag (G-Gaia) on 2021-10-09.6125. There is a possible counterpart of g = 22.32 in the PS1 Mean object catalog.

Our spectrum shows a blue continuum, the He II lines (4686 and 5411 Å), a Bowen component (∼ 4640 Å), and the Hα line. The He II (4686 Å) and Hα lines show double-peaked profiles with separations of ∼ 700 km/s. These spectroscopic characteristics indicate that this object is likely a dwarf nova in the Milky Way Galaxy, not a nova in M31. The double-peaked line profiles suggest that this object has a large inclination angle (i.e., edge-on). Assuming the possible counterpart of g = 22.32 in the PS1 catalog is the progenitor, its amplitude is around 7 mags. Such a large amplitude suggests this dwarf nova as a WZ Sge-type.

Optical spectrum of PNV J00444033+4113068