Spectroscopic confirmation and photometry of the nova candidate AT 2023ax
ATel #15867; A. F. Valeev, A. S. Vinokurov, Y. N. Solovyeva, A. S. Sarkisyan, D. V. Oparin (SAO RAS)
on 20 Jan 2023; 16:28 UT
Credential Certification: Azamat Valeev (azamat@sao.ru)
Subjects: Optical, Nova, Transient, Variables
Referred to by ATel #: 15926
ATels #15850 reported the discovery of M31 AT 2023ax (XM94MZ, PNV J00430924+4117022, ZTF23aaaairl), a new nova candidate in M31. We present the results of recent optical spectroscopy and photometry results and dissuss it's classification.
Spectroscopic observations were carried out with the multi-mode focal reducer SCORPIO-2 mounted at the primary focus of a 6-m SAO RAS telescope on 2023 Jan. 19 (MJD=59963.66), about 11 days after maximum according to the photometry reported by Zhang at al. (http://xjltp.china-vo.org/xm94mz.html). Three subexposures of 600s were obtained with a VPHG1200@540 grism covering the spectral range of about 3650-7300ÅÅ with resolution of 4.5Å. Spectroscopy has revealed the multipeak hydrogen lines, Na I blended with possible He I 5876, and also numerous Fe II emissions. The FWHMs of the hydrogen and Fe II emissions are in range of 2300-2700 km/s. Two clearly visible components in Hα and Hβ separated by about 1100 km/s.
During the imaging and spectroscopy the cirusses were crossing the sky and the seeing was about 1.5 arcsec. The estimated magnitudes are B = 18.93 ± 0.07, V = 18.91 ± 0.09, Rc = 18.70 ± 0.08. We use the Massey's M31 catalog (Massey et al. 2006, AJ, 131, 2478) stars as the reference for absolute calibration.
Based on the obtained spectrum the most preferable classification is Fe II nova. However, the possible detection of He I 5876A on our spectrum hints that the M31 AT 2023ax may belong to the hybrid subtype which is evolving into classic He/N, as it was in the M31 2006-10b case (Shafter et al. 2011, ApJ, 734, 12).
The work was performed as part of the government contract of the SAO RAS approved by the Ministry of Science and Higher Education of the Russian Federation. Observations with the SAO RAS telescopes are supported by the Ministry of Science and Higher Education of the Russian Federation. The renovation of telescope equipment is currently provided within the national project "Science and Universities".
The spectrum can be found here
