  The SN1987A in the Giant Magellanic Cloud was an amazing and extraordinary
event because it was detected in real time for different neutrinos experiments
($\nu$s) around the world. Approximate $\sim25$ events were observed in three
different experiments: Kamiokande II (KII) $\sim 12$,
Irvine-Michigan-Brookhaven (IMB) $\sim 8$ e Baksan $\sim 5$, plus a contrived
burst at Mont Blanc (Liquid Scintillator Detector - LSD) later dismissed
because of energetic requirements (Aglietta et al. 1988). The neutrinos have an
important play role into the neutron star newborn: at the moment when the
supernova explodes the compact object remnant is freezing by neutrinos
($\sim99\%$ energy is lost in the few seconds of the explosion). The work is
motivated by neutrinos' event in relation arrival times where there is a
temporal gap between set of events ($\sim6\mbox{s}$). The first part of dataset
came from the ordinary mechanism of freezing and the second part suggests
different mechanism of neutrinos production. We tested two models of cooling
for neutrinos from SN1987A: 1st an exponential cooling is an ordinary model of
cooling and 2nd a two-step temperature model that it considers two bursts
separated with temporal gap. Our analysis was done with Bayesian tools ({\it
Bayesian Information Criterion} - BIC) The result showed strong evidence in
favor of a two-step model against one single exponential cooling
($\ln\mbox{B}_{ij} > 5.0$), and suggests the existence of two neutrino bursts
at the moment the neutron star was born.
