The standard model for Type II supernovae explosion , confirmed by the detection of the neutrinos emitted during the supernova explosion , predicts the formation of a compact object , usually assumed to be a neutron star .
However , the lack of the detection of a neutron star or pulsar formed in the SN 1987A still remains an unsolved mystery .
In this paper we suggest that the newly formed neutron star at the center of SN1987A may undergo a phase transition after the neutrino trapping time scale ( \sim 10 s ) .
Consequently the compact remnant of SN 1987A may be a strange quark star , which has a softer equation of state than that of neutron star matter .
Such a phase transition can induce the stellar collapse and result in a large amplitude stellar oscillations .
We use a three dimensional Newtonian hydrodynamic code to study the time evolution of the temperature and density at the neutrinosphere .
Extremely intense pulsating neutrino fluxes , with submillisecond period and with neutrino energy ( > 30 MeV ) can be emitted because the oscillations of the temperature and density are out of phase almost 180 ^ { \circ } .
If this is true we predict that the current X-ray emission from the compact remnant of SN 1987A will be lower than 10 ^ { 34 } erg s ^ { -1 } , and it should be a thermal bremsstrahlung spectrum for a bare strange star with surface temperature of around \sim 10 ^ { 7 } K .