  The strange timing property of X-ray pulsar 1E 1207.4-5209 can be explained
by the hypothesis that it is a member of an ultra-compact binary system. This
paper confronts the ultra-compact assumption with the observed properties of
this pulsar. The gravitational potential well of an ultra-compact binary can
enlarge the corotation radius and thus make it possible for accreting material
to reach the surface of the NS in the low accretion rate case. Thus the
generation of the absorption features should be similar to the case of
accreting pulsars. The close equality of the energy loss by fast cooling of the
postsupernova neutron star and the energy dissipation needed for a wide binary
evolving to an ultra-compact binary demonstrates that the ultra-compact binary
may be formed in 10-100yr after the second supernova explosion. Moreover, the
ultra-compact binary hypothesis can well explain the the absence of optical
counterpart and the observed two black body emissions. We suggest a simple
method which can test the binary nature directly with XMM-Newton and Chandra
observations. We further predict that the temperature of the two black bodies
should vary at different pulse periods.
