Studies of the flickering in cataclysmic variables
VI. The location of the flickering light source in
V2051 Ophiuchi, IP Pegasi and UX Ursae Majoris
Laboratório Nacional de Astrofísica, CP 21,
BR-37500-000 Itajubá - MG, Brazil, e-mail: email@example.com
The scatter in the light curves of four eclipsing cataclysmic variables
is analyzed in order to find constraints for the location of the flickering
light source in these systems. In all cases the ``scatter curves'' contain
well defined eclipses which begin and end exactly at the phases of eclipse
ingress and egress of individual system components: In HT Cas, V2051 Oph
and UX UMa the scatter
eclipse coincides with the white dwarf eclipse, in IP Peg
with the hot spot eclipse. Moreover, in V2051 Oph, IP Peg and UX UMa the
scatter is enhanced during phases of visibility of the hot spot. Together
with similar results from earlier investigations these findings leave little
doubt that the flickering in CVs can originate in two regions: the innermost
accretions disk with the boundary layer and the white dwarf surface, and the
region of impact of the stream of transferred matter from the secondary
the accretion disk. Two different techniques (termed 'single' and 'ensemble'
method) to measure the scatter curves of CVs are advocated in the
literature. A critical comparison of these techniques is performed.
It is found that the 'ensemble'
method yields reasonable results only under specific circumstances.
Stars: variables: general - binaries: eclipsing
- Stars: novae, cataclysmic variables - Stars: individual: HT Cas,
V2051 Oph, IP Peg, UX UMa