SDSS J085414.02+390537.3—A New Asynchronous Polar

Abstract

Based on data from the ZTF photometric survey, we have revealed asynchrony of the polar SDSS J085414.02+390537.3. A beat period Pbeat = 24.6 ± 0.1 days, during which the system changes its brightness by ≈3m , is distinguished in the light curves. Power peaks at the white-dwarf rotation period Pspin = 113.197 ± 0.001 min and orbital period Porb = 113.560± 0.001 min are revealed in the periodograms, with the corresponding polar asynchrony being 1 − Porb/Pspin = 0.3%. . The photometric behavior of the polar points to a change of the main accreting pole during the beat period. Based on the Zeeman splitting of the Hβ line, we have estimated the mean magnetic field strength of the white dwarf to be B = 28.5 ± 1.5 MG. The magnetic field strength near the magnetic pole has been found by modeling the cyclotron spectra to be B = 34± 2 MG.. The Doppler tomograms in the Hβ line exhibit a distribution of emission sources typical for polars in velocity space with evidence of the transition of the accretion stream from the ballistic trajectory to the magnetic one.