Ruling out red-giant and most main-sequence companions for the nearest modern Type Ia supernova, weeks after its discovery (Li, Bloom et al., Nature 2011).
Given on the symposium's second day, “Explosive or Irreversible Changes” (Tuesday, September 20), at the University of Oxford; the deck's title slide reads “IAU Oxford – 20 Sept 2011”. The talk has no paper in the proceedings, which are linked above; his invited review on the closing day is a separate entry.