A remarkable stellar event that mesmerized astronomers in 1843 may have been a previously unknown kind of explosion, researchers say. That explosion, which made the star Eta Carinae one of the brightest in the Southern sky, could have been the precursor to the star's expected explosion into a supernova. Researchers began watching Eta Carinae after the star mysteriously brightened 1843, and
astronomers in recent decades have photographed and studied the resulting cloud of gas and dust, known as the Homunculus Nebula, that billows away from the star. A farther-out faint shell of debris from an earlier explosion is also visible, probably dating from around 1,000 years ago. "Looking at other galaxies, astronomers have seen stars like Eta Carinae that get brighter, but not quite as bright as a real supernova," said [lead researcher] Nathan Smith.... "We don't know what they are. It's an enduring mystery as to what can brighten ...
