Everyone has been talking and writing about the new supernova, 1987A, so we might as well, too. In fact, we really must, because 1987A is more than usually anomalous. The newspapers have oohed and aahed about this rare opportunity scientists have to study a nearby supernova. However, instead of getting closer to a final understanding of supernovas, 1987A seems to be confounding the theorists.
No one can determine which star, if any, blew up. The 12th magnitude star Sanduleak -69 202 was first fingered, for it is located in the proper spot. But it is still there, apparently unchanged, as is a still fainter companion. The problem is that if 1987A really originated with an even fainter star, such a star would not have enough mass to go supernova.
Part of 1987A's spectrum, its luminosity evolution, and precursory neutrino burst all indicate a Type-II supernova. Unfortunately, its ultraviolet spectrum is that of a Type-I supernova. Also anomalous are its high rate of evolution and low luminosity (only magnitude 4.5 instead of the predicted 2+.
Japanese apparatus located in a deep mine near Kamioka detected a burst of neutrinos about 22 hours before 1987A flared into the visible spectrum. This fits Type-II supernova theory, but the Mont Blanc equipment detected a neutrino burst just 4.6 hours before the flare-up. Which detector is correct; and why didn't both detectors register both bursts, if such there were? At the moment, some scientists think that the Mont Blanc event was spurious in view of previous unexplained bursts recorded there.
(Waldrop, M. Mitchell; "The Supernova 1987A Shows a Mint of Its Own -- and a Burst of Neutrinos," Science, 235:1322, 1987.)
Reference. See AOF5 in our catalog: Stars, Galaxies, Cosmos, for more supernova anomalies. Ordering information here.