Optical and X-ray studies of three polars: RX J0859.1+0537, RX J0749.1-0549, and RX J0649.8-0737

TL;DR

This study analyzes optical and X-ray data of three polars, revealing their orbital periods, eclipse characteristics, magnetic field strengths, and accretion region properties, with implications for understanding magnetic cataclysmic variables.

Contribution

First detailed optical and X-ray analysis of three polars, determining their orbital periods, eclipse features, and magnetic field strengths, expanding knowledge of magnetic cataclysmic variables.

Findings

RX J0859.1+0537 is an eclipsing polar in the period gap.

RX J0749.1-0549 and RX J0649.8-0737 are long-period eclipsing polars.

Magnetic field strengths are approximately 49 MG, 43.5 MG, and 44 MG for the three systems.

Abstract

We present optical photometric and spectroscopic observations, and an analysis of archival X-ray data of three polars: RX J0859.1+0537, RX J0749.1-0549, and RX J0649.8-0737. Optical light curves of these three polars reveal eclipse features that are deep, total, and variable in shape. The optical and X-ray modulations of RX J0859.1+0537, RX J0749.1-0549, and RX J0649.8-0737 are both found to occur at the orbital periods of 2.393$\pm$0.003 hrs, 3.672$\pm$0.001 hrs, and 4.347$\pm$0.001 hrs, respectively. RX J0859.1+0537 is found to be an eclipsing polar which lies in the region of the period gap, whereas RX J0749.1-0549 and RX J0649.8-0737 are found to be long-period eclipsing polars above the period gap. The eclipse length is found to be 61 min for RX J0749.1-0549 in the R-band, which is the highest among the long period eclipsing polars. The radius of the eclipsed light source is found to be more than the actual size of the white dwarf for these three systems, indicating that the eclipsed component is not only the white dwarf but also appears to include the presence of an extended accretion region. Optical spectra of these systems show the presence of high ionization emission lines along with the strong Balmer emission lines with an inverted Balmer decrement. Cyclotron harmonics are also detected in the optical spectra from which we infer magnetic field strength of the surface of the white dwarf to be 49$\pm$2 MG, 43.5$\pm$1.4 MG, and 44$\pm$1 MG for RX J0859.1+0537, RX J0749.1-0549, and RX J0649.8-0737, respectively.