SDSS J085414.02+390537.3 -- a new asynchronous polar

TL;DR

This paper reports the discovery and analysis of a new asynchronous polar, SDSS J085414.02+390537.3, revealing its beat period, white dwarf spin and orbital periods, magnetic field strength, and accretion behavior through photometric and spectroscopic data.

Contribution

It provides the first detailed characterization of this asynchronous polar, including its beat period, magnetic field, and accretion pole changes, using ZTF photometry and spectroscopic modeling.

Findings

Beat period of 24.6 days with brightness variation of 3 magnitudes.

White dwarf spin period of 113.197 minutes and orbital period of 113.560 minutes.

Magnetic field strength estimated at approximately 28.5 MG from Zeeman splitting and cyclotron modeling.

Abstract

The asynchrony of the polar SDSS~J085414.02+390537.3 was revealed using the data of ZTF photometric survey. The light curves show a beat period $P_{beat} = 24.6 \pm 0.1$~days. During this period the system changes its brightness by $\sim 3^m$. The periodograms show power peaks at the white dwarf's rotation period $P_{spin} = 113.197 \pm 0.001$~min and orbital period $P_{orb} = 113.560 \pm 0.001$~min with the corresponding polar asynchrony $1-P_{orb}/P_{spin} = 0.3\%$. The photometric behavior of the polar indicates a change of the main accreting pole during the beat period. Based on the Zeeman splitting of the H$\beta$ line, an estimate of the mean magnetic field strength of the white dwarf is found to be $B = 28.5\pm 1.5$~MG. The magnetic field strength $B \approx 34$~MG near the magnetic pole was found by modeling cyclotron spectra. Doppler tomograms in the H$\beta$ line demonstrate the distribution of emission sources typical for polars.