Abstract
We have carried out a comprehensive study of the poorly investigated eclipsing polar
1RXS J184542.4+483134 with a short orbital period Porb ≈ 79 min. An analysis of its long-term light
curves points to a change in the position and sizes of the accretion spot as the accretion rate changes.
Narrow and broad components, which are probably formed on the ballistic segment of the accretion stream
and on the magnetic trajectory, respectively, are identified in the emission line profiles. An inversion of
the line profiles from emission to absorption due to the obscuration of the accretion spot by the accretion
stream is observed. Based on the eclipse duration and the radial velocities of the narrow line component,
we impose constraints on the white dwarf mass, 0.49 ≤ M1/M ≤ 0.89, and the orbital inclination,
79.7◦ ≤ i ≤ 84.3◦. An analysis of the cyclotron spectra points to the presence of two accretion spots
with magnetic field strengths B1 = 28.4+0.1
−0.2 MG and B2 = 30 − 36 MG. The main spot has a complex
structure that apparently has a dense core and a less dense periphery emitting a spectrum with cyclotron
harmonics. Polarization observations reveal a circular polarization sign reversal during the orbital period
and an anticorrelation of the polarization with the brightness of the polar. Our modeling of polarization
observations using the simple model of an accreting white dwarf shows that the polarization properties
can be interpreted in terms of two-pole accretion with different optical depths of the accretion spots
(τ1/τ2 ∼ 10). An analysis of the Swift/XRT observations points to a predominance of bremsstrahlung
in the X-ray radiation from the system.