Core-collapse supernovae

Association of ccSNe
with HII regions in M51

Core-collapse supernovae involve the death of massive stars, whose lifetimes are 5-50 Myr. As such, they might be expected to be associated with star-forming regions. Historical ground-based surveys (approx 0.1 kpc spatial resolution) identified a majority of type II and Ib/c ccSNe with HII regions, while more recent studies have indicated differences amongst the different ccSNe flavours, with an increasing likelyhood of HII region association for type II, Ib and Ic supernovae. We interpret this difference to the longer lifetime of many type II-P progenitors (up to 50 Myr) than the 10-20 Myr duty cycle of giant HII regions. In contrast, if type Ib/c progenitors have shorter lifetimes (up to 20 Myr), most will be associated with giant HII regions. The accompanying figure shows the immediate environment of recent ccSNe in M51, ranging from no association (SN 2011dh, II-P), association with a faint Orion-like nebula (SN 2005cs, II-P) and association with a bright HII region (SN 1994I, Ic). From inspection of high spatial resolution (approx 10 pc) imaging, a very small fraction of ccSNe are associated with compact HII regions whose duty cycles are much shorter (approx 5 Myr).