SRGe J214919.3+673634—a Candidate for AM Her Variables Discovered by the eROSITA Telescope onboard the Spectrum-Roentgen-Gamma Orbital Observatory

We present the results of the optical identification, classification, and analysis of our photometric and spectroscopic observations of the X-ray transient SRGe J214919.3+673634 discovered by the eROSITA telescope onboard the Spectrum-Roentgen-Gamma orbital observatory in the summer of 2021 during the fourth sky survey. The photometric observations of the optical counterpart of SRGe J214919.3+673634 performed at the 6-m BTA telescope of SAO RAS, the 1.5-m Russian-Turkish telescope RTT-150, and the 2.5-m telescope of CMO SAI MSU as well the archival data from the 48-inch ZTF telescope have shown that the source is a cataclysmic variable with an orbital period P=85± 0.4 min and exhibits a long-term photometric variability from 23.5^m (low state) to 20^m (high state). We show that the light curves in the high state are consistent with the model of an accreting magnetized white dwarf and suggest that SRGe J214919.3+673634 belongs to the AM Her variables. The spectra of the optical counterpart taken in the low state at BTA are consistent with the spectral energy distribution of a white dwarf with a temperature ∼24,000 K.