DELAYED DETONATION MODELS FOR NORMAL AND SUBLUMINOUS TYPE IA SUPERNOVAE - ABSOLUTE BRIGHTNESS, LIGHT CURVES, AND MOLECULE FORMATION

We compute optical and infrared light curves of the pulsating class of delayed detonation models for Type Ia supernovae (SN Ia's) using an e laborate treatment of the LTE radiation transport, equation of state a nd ionization balance, expansion opacity including the cooling by CO, CO+, and SiO, and a Monte Carlo gamma-ray deposition scheme. The model s have an amount of Ni-56 in, the range from similar or equal to 0.1 M . up to 0.7 M. depending on the density at which the transition from a deflagration to a detonation occurs. Models with a large nickel produ ction give light curves comparable to those of typical Type Ia superno vae. Subluminous supernovae can be explained by models with a low nick el production. Multiband light curves are presented in comparison with the normally bright event SN 1992bc and the subluminous events SN 199 1bg and SN 1992bo to establish the principle that the delayed detonati on paradigm in Chandrasekhar mass models may give a common explosion m echanism accounting for both normal and subluminous SN Ia's. Secondary IR-maxima are formed in the models of normal SN Ia's as a photospheri c effect if the photospheric radius continues to increase well after m aximum light. Secondary maxima appear later and stronger in models wit h moderate expansion velocities and with radioactive material closer t o the surface. Model light curves for subluminous SN Ia's tend to show only one ''late'' IR-maximum. In some delayed detonation models shell -like envelopes form, which consist of unburned carbon and oxygen. The formation of molecules in these envelopes is addressed. If the model retains a C/O-envelope and is subluminous, strong vibration bands of C O may appear, typically several weeks past maximum light. CO should be very weak or absent in normal SN Ia's.