Star search

BRONWYN CHESTER | A stellar mystery may have been solved. Last year a German-U.S. satellite detected the glowing remnant of a supernova 640 light years away whose explosion would have been visible on earth at the beginning of the 14th century. What was baffling was that there was no record of the event despite the fact that for several weeks the night sky would have been as brightly lit as it is during the full moon and despite the fact that astronomers of the medieval period kept good records. Along came Professor Clifford Burgess, theoretical particle physicist, and his colleague Kai Zuber, an experimental particle physicist from Dortmund University in Germany. For the past five years, the two friends had, as a hobby, been searching for evidence on earth of a different supernova, the Geminga (Italian for "it doesn't exist"), known to have exploded 500,000 years ago. They believed that the trace on earth left by the supernova, which is an explosion of a star many times bigger than the sun and much farther away, would be in the form of trace radioactive particles, neutrinos, in rock. Then, while perusing the literature, Zuber stumbled upon the work of Robert Rood (et al) done in 1979. Rood's analysis of an ice core extracted from the South Pole showed four "spikes" of nitrate concentration at different depths in the ice, three of which corresponded to the dates of supernovas recorded by astronomers of earlier centuries. There was Kepler's Supernova of 1604, Tycho's of 1572 and Supernova "3C58" of 1181. The spikes are believed to be the result of nitrates formed when blast waves of ionising radiation from the three supernova explosions struck the earth's atmosphere. Those particles would have settled on the surface of Antarctica, creating a glacial record of the event. The date of the explosion is determined by comparing the depth of the spike with the mean rate of snowfall in the area. While none of those dates corresponded to the Geminga, the fourth and unaccounted for spike remained in the minds of the two physicists. And, as the cosmos would have it, Burgess and Zuber, while leafing through journal articles over a coffee last fall in Indigo Books, fell upon the report of this most recent supernova discovery by satellite. Lo and behold, if the date of the explosion's appearance to an earthling's eye didn't correspond to the date of the fourth spike! It was one of those moments of: "Are you thinking what I'm thinking?" Burgess recalls. "It was a complete fluke. "This fourth spike corresponds precisely with the time when light -- including X-rays and gamma rays -- from the recently discovered Vela Supernova would have been arriving at the Earth," said Zuber in the current New Scientist. After writing the article about their deduction, and posting it on the Astrophysics web site in Los Alamos, New Scientist and Reuters caught wind of the discovery and Burgess found his work getting media coverage for the very first time. Theoretical particle physics, Burgess's main line of research, doesn't attract much attention. "Usually, I'm just sitting around with a coffee," he says with a laugh, "trying to understand the rules governing the behaviour of atoms and their constituent particles." Burgess also teaches a graduate course in physics and the popular "Planets, Stars and Galaxies," an introduction to astronomy for non-physicists. Now that the riddle of the Vela Supernova seems to have been solved, he and Zuber will get back to Geminga. Burgess thanks the Internet for giving him and Zuber access to data from ice and rock analyses which normally would not be available to a particle physicist -- being more the domain of the likes of geophysicists and climatologists and the others seeking answers regarding the near and distant past of both earth and outer space.