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Project Progress

The presence of short-lived radionucleides (SLRs) in meteorites, particularly 60-Fe, suggests that our solar system formed in close proximity to a supernova. It has been suggested that our Sun’s formation was triggered by the compression of surrounding molecular gas by the blast wave, or even that the proto-planetary disk itself was directly impacted with supernova ejecta. By compiling the latest statistics on young star clusters including their number distribution, density profile, and expansion speed, we have derived an expression for the probability of a sun-like star being within a specified distance of a massive star as it explodes.

We estimate that only about 1 in100 proto-planetary disks are close enough to a supernova to be ejected with the observed level of SLRs in our Solar System. However, 1 in 10 stars are close enough for their formation to have potentially been triggered by the supernova. This is an order of magnitude higher than previous estimates and helps to reconcile a glaring discrepancy with cosmochemical data. A paper is in the early stages of preparation.

This work began out of discussions in the joint astronomy-geology course, “Formation of solar systems”, co-taught by Williams, Krot and Gaidos. One of the registered graduate students, Dagny Looper, looked into previous work on this problem for her term paper and this spurred our new work.