The model proposed here for planet formation around millisecond pulsars is a natural consequence of irradiation-driven evolution of low-mass X-ray binaries (LMXBs) and SVPs[5] as qualitatively suggested in [1] in the case of PSR1257+12 and in [9] in the case of PSR1957+20.
Let us discuss the SVP case first. The discovery of 'star-vaporizing
pulsars' such as PSR1957+20 and PSR1744-24A confirmed the relevance of
star irradiation and consequent mass loss on the binary evolution of
millisecond pulsars[5]. The pulsar wind interacts with the mass
outflow and forms a termination shock where electron-positron pairs
may be efficiently acceler- ated and emit synchrotron radiations. The
radiation spectrum depends on the details of the shock acceleration
mechanism and on the composition of the pulsar wind (see, for example,
[12]). The effect of star irradiation is to produce a large
temperature (
)
mass outflow[5,13] which is reprocessed by
a shock occurring where the pulsar radiation pressure balances the gas
pressure. Complex hydrodynamical processes contribute to give the
final pressure and velocity configuration of the material which then
moves out from the binary. Detailed calculations of the mass outflows
of PSR1957+20 and PSR1744-24A [7,8] and the eclipse properties
of these two systems show that the mass outflow configuration can have
different shapes and that the pulsar can be completely enshrouded[14] by
the evaporated material, as occasionally happens for PSR1744-24A
[3].