Key link found in Cosmic Distance Ladder

When observing the bright explosion of a White Dwarf star in our neighbouring galaxy last year, researchers from The Australian National University collected the largest ever data set on what they recognised as one of our best 'standard candles' yet for distance measurements in the Universe. "We know how a candle of a particular brightness grows fainter as it is moved further away from us. So, if we know the true brightness of the candle (in this instance, supernova SN 2012fr) and we measure its observed brightness, we can then calculate the interceding distance," said Dr Michael Childress. Supernova SN 2012fr left a chemical fingerprint which has been analysed by a team of researchers led by Dr Childress from the ANU Research School of Astronomy and Astrophysics and which also includes Nobel Laureate Professor Brian Schmidt. Their data shows unprecedented, and quite unusual, layering in the material that was burnt and ejected in the explosion, especially silicon and iron. Two distinct layers of silicon were found: one thick, outer layer that had faded by the time the supernova reached its peak brightness on 12 November 2012 (16 days after the initial explosion), and one deeper layer that hardly changed for several weeks after the explosion. "As it turns out, SN 2012fr is not just another supernova but a really interesting case.