€Zwaan & Verbunt suggested that at 3hr the magnetic braking switches off,
because secondaries with this mass are fully convective, so stellar dynamo is quenched
€Mass transfer rate then is reduced, so secondary falls
away from Roche Lobe, and mass transfer stops, so these
systems are not seen as CVs
€Then gravitational radiation would continue to operate,
slowly driving the two stars together, until contact with the
Roche Lobe was reestablished and accretion restarted: the
origin of the <2hr binaries
€While this has been the ³standard² explanation for some time, questions have always remained about the real
effect of fully convective secondaries on the generation of
magnetic field by the dynamo
€Some evidence for this mechanism clear from the absence of
a significant gap in the magnetic systems, in which
braking is affected by the field from the primary (in addition to
that from the secondary)