Book Reviews

Stream Eclipse Mapping with ‘Fire-Flies’

“…The HU Aqr data presented here has been modeled previously with a version of the technique of Harrop-Allin et al (1999a). This method was found to be acutely sensitive to the exact value chosen for the distance to the threading region, and also the location of the accretion region on the white dwarf surface, which fixes the geometry of the magnetic field lines (Bridge et al 2002).…”

“…However with this new technique we do not see much enhancement where we expect material to be threaded by the field lines. The technique of Harrop-Allin et al (1999a) was also applied to other observations of HU Aqr (Harrop-Allin et al 1999b). They found that there was generally enhanced brightness towards the white dwarf and in the threading region, and for some cycles the threading region was significantly brighter.…”

“…This shows that the trajectory is largely as expected, with the model providing good fits to the light curves of HU Aqr and EP Dra. The different results obtained from modeling the same data imply some dependence upon the technique, although this new technique is less sensitive to input parameters than that of Harrop-Allin et al (1999a). A more detailed investigation of the effects of the input parameters and the regularisation curve is needed to fully understand any effects.…”

“…This was represented as an arc connecting the inner Lagrangian point (L 1 ) to the white dwarf. Developments to this method included a two part trajectory, and models using this have been successfully applied to the eclipse light curves of the bright eclipsing polars HU Aqr and UZ For (Bridge et al 2002;Vrielmann & Schwope 2001;Harrop-Allin, Potter & Cropper 2001;Kube, Gänsicke & Beuermann 2000;Harrop-Allin et al 1999b). This trajectory comprises a ballistic free-fall component from the L 1 -point (Lubow & Shu 1975), followed at some distance from the white dwarf by a 2 Bridge, Hakala, Cropper & Ramsay magnetically confined component.…”