Itty Bitty SuperNovae

Everything changes.

Over on Bad Astronomy, Phil Plait has a post up talking about SN 2006bc. This wasn’t a particularly spectacular supernova, like SN 2006gy (also see my articles here and here) or SN 2005ap. However, it is interesting because it was part of a 10-year study by astronomers from Queen’s University Belfast in Northern Ireland, led by Professor of Astronomy Stephen J. Smartt. The results of this study will be presented at an upcoming meeting in the U.K.

From the spacetelescope.org site:

“In their latest work on Hubble images, to be presented at the UK National Astronomy Meeting 2008 in Belfast, the Queen’s team reveals the results of their ten-year search for these elusive supernova precursor stars. It appears that stars with masses as low as seven times the mass of the Sun can explode as supernovae. The team have not found any very massive stars that exploded, suggesting that the most massive stars may collapse to form black holes either without producing a supernova or by producing one that is too faint to observe. This intriguing possibility will be discussed at the meeting.”

There are two things in this paragraph I find intriguing. First, current models predict that type-II (core collapse) supernovae should occur in stars with masses of over 9Msun. The fact that they have found smaller stars as precursors of type-II supernovae means that our models may need a bit of tweaking. Second, the bit about the most massive stars collapsing without producing a supernova is also intriguing but seems a bit more speculative. The usual caveats about cutting-edge science apply. These results will be vetted by people way smarter than me, and probably argued over for years before the astronomers reach a consensus.