Polarimetry of QQ Vul

This paper presents an investigation of the polarization behaviour of the AM Her system QQ Vul at several epochs over 3 years. There are changes of a factor of 2 in the amplitude of the orbitally phased circular polarization from epoch to epoch. The mean behaviour can be modelled with an accretion arc ahead of and closer to the orbital plane than the magnetic pole, but it has proven difficult to link the changes in polarization with changes in the location of the accretion region. The paper concludes with an investigation into whether the variations are periodic, but the evidence for this is marginal.     

An electrically powered binary star?

We propose a model for stellar binary systems consisting of a magnetic and a non-magnetic white dwarf pair which is powered principally by electrical energy. In our model the luminosity is caused by resistive heating of the stellar atmospheres arising from induced currents driven within the binary. This process is reminiscent of the Jupiter–Io system, but greatly increased in power because of the larger companion and stronger magnetic field of the primary. Electrical power is an alternative stellar luminosity source, following on from nuclear fusion and accretion. We find that this source of heating is sufficient to account for the observed X-ray luminosity of the 9.5-min binary RX J1914+24, and provides an explanation for its puzzling characteristics.