The star exhibits variations in the timing and shape of its pulses: this was at one stage interpreted as due to a possible planetary system in orbit around the pulsar, though the model required an anomalously large second period derivative of the pulse times.
[3] The planetary model was later discarded in favour of precession effects as the planets could not cause the observed shape variations of the pulses.
[4][5] While the generally accepted model is that the pulsar is a neutron star undergoing free precession,[6] a model has been proposed that interprets the pulsar as a quark star undergoing forced precession due to an orbiting "quark planet".
[7] The entry for the pulsar on SIMBAD lists this hypothesis as being controversial.
This variable star–related article is a stub.