.If we assume that OBP-B1 has produced at least one supernova, when did that supernova (or supernovae) go off? This figure presents the PDF of time elapsed since a supernova explosion, heavily favoring more recent supernova explosions. For example, there is roughly a 15% chance of a supernova exploding 1-3 Myr ago in OBP-B1, which is 3 times more likely than a supernova exploding 5-7 Myr ago.