Variability of the Spin Period of the White Dwarf in the Intermediate Polar V405 Aur: Low-Mass Third Body or Precession ?

TL;DR

This study investigates the variability in the white dwarf's spin period in the V405 Aur system, proposing hypotheses involving either precession or a third body causing periodic light-time effects.

Contribution

It introduces two hypotheses for the spin period variability, including the potential presence of a low-mass third body influencing the system.

Findings

Spin period in 2010-2012 is approximately 545.4558163 seconds.

Possible periodic change with a 6.2-year cycle and 17.2 sec amplitude.

Light-time effect suggests a low-mass third star in the system.

Abstract

We present the results of photometric CCD observations of the magnetic cataclysmic variable V405 Aurigae (RX J0558.0+5353 = 1RXS J055800.7+535358) obtained using different instruments. We analysed variability of the spin period of the white dwarf in the V405 Aur (RX J0558.0+5353) system using our observations and previously published maxima timings. The spin period of the system in 2010-2012 is $P=545.4558163(94)$s. As we have gaps in observational data, we present 2 hypotheses of the spin period variability of this system - a cubic ephemeris which may be interpreted by a precession of the magnetic white dwarf or a periodic change with a period of 6.2 years and semi-amplitude of $17.2\pm1.8$ sec. The periodic variations may be interpreted by a light-time effect caused by a low-mass star ($M_3\ge0.09M_\odot$). In this case, the system belongs to a rare class of cataclysmic variables with a third body.