Sn1987a Revisited after 20 Years: May the Supernova Bang More Than Once?

Understand

The observations of supernova 1987A in underground detectors are revisited.

• It is shown that, while the LSD detector in the Mont Blanc Laboratory observed only one burst at 2h 52min 36.8sec U.T., the Kamiokande data show a possible second burst, in addition to the well known one at 7h 35min 33.7sec U.T.
• This second burst consists of a cluster of seven pulses, well above the energy threshold of the detector, observed during 6.2 seconds starting at 7h 54min 22.2sec U.T.
• Do these observations imply a long duration of the collapse?