Secondary Parameters of Type Ia Supernova Light Curves
  High-quality observations of $B$ and $V$ light curves obtained at Las
Campanas Observatory for local Type Ia Supernovae (SNe Ia) show clear evidence
that SNe Ia with the same brightness decline or stretch may have systematic and
independent deviations at times < 5 days before and at times > 30 days after
maximum light. This suggests the existence of two independent secondary
parameters which control the shape of SN Ia light curves in addition to the
brightness decline relation. stretch. The differences are consistent in
morphology of the time dependence and size with predictions by models within
the delayed detonation scenario. The secondary parameters may reflect two
independent physical effects caused by variations in the progenitor and
accretion rates, and link the LC variations in shape with the intrinsic,
absolute brightness.
