From: YKhan on
Supernova uncertainty
"But the star's chemical composition doesn't fit with the model of an
exploding white dwarf star either – the material expelled in SN 2005E
contains a higher fraction of calcium and titanium than any supernova
observed so far. Instead, this signature is more typical of nuclear
reactions involving helium, rather than the carbon and oxygen found in
the centre of typical white dwarf stars. "
http://www.astronomynow.com/news/n1005/20sn/