Bibcode
Rodríguez-Gil, Pablo; Potter, Stephen B.
Bibliographical reference
Monthly Notice of the Royal Astronomical Society, Volume 342, Issue 1, pp. L1-L4.
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6
2003
Citations
7
Refereed citations
6
Description
We report on the discovery of variable circular polarization from the
remnant of Nova Chamaeleontis 1953 (RR Cha). The circular polarization
appears to be modulated on the spin period of the primary and harmonics
of the positive superhump period, with an amplitude peak-to-peak of
almost ~10 per cent with both negative and positive polarization.
A recent study by Woudt & Warner of RR Cha shows it to have both
positive and negative superhumps, indicating the presence of a
precessing/tilted accretion disc. In addition, they also find a stable
period at 1950 s, characteristic of an intermediate polar. RR Cha also
shows deep eclipses with variable depth.
We propose a possible explanation for the origin of the polarized
emission. We assume that it is of cyclotron origin. The variations of
the circular polarization with the proposed spin period are caused by
the rotation of the compact object. The long-period variability arises
as a result of a precessing/tilted accretion disc, periodically
obscuring either of two accretion regions on the surface of the white
dwarf.
We also point out several similarities of RR Cha to the SW Sex stars.
The lack of a time-resolved spectroscopic study prevents any conclusion
regarding its possible SW Sex nature. Hence such spectroscopic study is
encouraged.
RR Cha is the second old nova exhibiting variable circular polarization,
and we therefore encourage polarimetric observations of other nova
remnants.