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2003MNRAS.339..685R - Mon. Not. R. Astron. Soc., 339, 685-694 (2003/March-1)
Multi-epoch spectroscopy, polarimetry and photometry of the polar UW Pic.
ROMERO-COLMENERO E., POTTER S.B., BUCKLEY D.A.H., BARRETT P.E. and VRIELMANN S.
Abstract (from CDS):
We put forward a scenario that explains our observations in terms of changing accretion rates of UW Pic coupled with a particular orientation of the system to the observer. In addition, we have modelled the polarimetric observations according to this scenario. During epochs of lower rates, accretion occurs preferentially on to the magnetic pole that is most pointing towards the observer and the secondary star (the upper pole), resulting in negative circular polarization over the whole orbit and more Caii (λ3933) emission. During epochs of higher rates, accretion occurs preferentially on to the opposite (lower) magnetic pole, though some accretion still occurs on to the upper pole. This results in both signs of polarization being observed. The higher accretion rate produces more Heii (λ4686), a lower percentage of polarization and, due to geometrical considerations, a lower amount of Caii (λ3933) emission. Alternatively, we note that these morphological variations are also suggestive of an asynchronous polar. Although we cannot rule out this scenario at present, no strong evidence of asynchronicity has been observed in our longest consecutive data sets, implying a beat period (if present) of the order of months.
Abstract Copyright: RAS
Journal keyword(s): accretion, accretion discs - methods: analytical - techniques: polarimetric - techniques: spectroscopic - binaries: close - novae, cataclysmic variables
Simbad objects: 5
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