Doppler Tomography and Photometry of the Cataclysmic Variable 1RXS J064434.5+334451

TL;DR

This study combines photometry and spectroscopy to analyze the cataclysmic variable 1RXS J064434.5+334451, revealing system parameters, emission region structures, and classifying it as an SW Sex-type system.

Contribution

It provides improved ephemeris, detailed Doppler tomography, and component mass measurements for this specific cataclysmic variable, confirming its SW Sex classification.

Findings

Eclipses show internal structure indicating a central HeII emission region.

System has a high inclination angle of approximately 78 degrees.

Component masses are approximately 0.82 and 0.78 solar masses.

Abstract

We have obtained simultaneous photometric and spectroscopic observations of the cataclysmic variable 1RXS J064434.5+334451. We have calibrated the spectra for slit losses using the simultaneous photometry allowing to construct reliable Doppler images from H$\alpha$ and HeII 4686 emission lines. We have improved the ephemeris of the object based on new photometric eclipse timings, obtaining $HJD = 2453403.759533 + 0.26937446E$. Some eclipses present a clear internal structure which we attribute to a central HeII emission region surrounding the white dwarf, a finding supported by the Doppler tomography. This indicates that the system has a large inclination angle $i=78 \pm 2^{\circ}$. We have also analysed the radial velocity curve from the emission lines to measure its semi--amplitude, $K_1$, from H$\alpha$ and HeII 4686 and derive the masses of the components: $M_1=0.82\pm0.06$ M$_{\odot}$, $M_2=0.78\pm0.04$ M$_{\odot}$ and their separation $a=2.01\pm0.06$ $R_{\odot}$. The Doppler tomography and other observed features in this nova-like system strongly suggests that this is a SW Sex-type system.