No. 81: May-Jun 1992
There seems to be a mysterious "central compact object" lurking amid the debris of Supernova SN1987A. Prevailing supernova paradigms cannot account for this high density remnant. While some aspects of standard supernova theory were supported by observations made during and since the 1987 explosion, astrophysicists are left with several puzzles in addition to the mystery object itself:
"Other puzzles include the largescale asymmetries observed in the heavy element ejecta (Fe-group line emission), the supernova envelope (optical polarization), and the circumstellar medium ([O III] ring), which are in addition to the complex structures resulting from hydrodynamic instabilities."
(Chevalier, Roger A.; "Supernova 1987A at Five Years of Age," Nature, 355:691, 1992.)