Discovering Supernovae – 24th January 2008

On this clear evening just after full moon Tom Boles gave us an interesting talk on Discovering Supernovae. He began by explaining the differences between Type 1a supernovae (which happen when a white dwarf star which is accumulating material from a companion star grows beyond its maximum mass) and all the other types (which happen when massive stars run out of readily fusable fuel and suffer a core collapse). He then, after a short diversion explaining how supernova discoveries don’t happen, went on to explain the procedures involved in finding potential supernovae, testing them to determine whether they are genuinely new, and then reporting them if they pass the tests. Finding candidates is largely a matter of imaging a sufficient number of distant galaxies and then comparing the images with reference master images looking for differences. Collecting images is a process that can be made very much easier by using robotic telescopes with good computer control. The trickier part is searching for significant differences, and them making sure that the differences can’t be explained by anything other than a new supernova. Tom described the many ways differences might appear on images of  galaxy, from CCD errors and cosmic rays via variable stars and emission nebulae, to asteroids and artificial satellites. He then briefly mentioned some of the telescopes that have been used to confirm discoveries he has made. The list included the Keck telescopes, the Hubble Spase Telescope, and the Hale 200-inch telescope on Mt. Palomar. He ended his talk by describing some of the up-coming professional competition, and pointed out that though these will probably find a great many supernovae, they’ll tend to find them in the fainter and more distant galaxies, so there’ll still be a place for amateur supernova patrols for many years to come.

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