(Proposal ID) S12A-047

(PI) Maeda, Keiichi

(Proposal Title)
Nucleosynthesis and Molecular Formation in Supernovae

(Abstract)

We propose to take late-time zJ/J, H, K band spectra and photometry for 
supernovae (SNe), at about >200 days since the explosion, using IRCS and 
LGS-AO. The late-time spectra contain a wealth of information about the 
element abundance (J & H) and molecular formation in SNe (K), but have been 
obtained for only a few SNe, especially missing for thermonuclear SNe (SNe Ia) 
and stripped SNe (SNe IIb/Ib/c). The new AO system together with recent 
unprecedented discovery of a few very nearby SNe Ia and IIb provide a 
possibility to tackle to this unexplored field. Analyzing [Fe II] in J & H 
(especially for SNe Ia) and various emission lines from intermediate elements 
(especially for stripped SNe) provides a closer view on the explosion 
mechanisms than in optical. Since these lines are produced at the deepest 
part of the ejecta and reach us without further interactions in the late-phase,
 the line profile analysis is especially a strong and unique tool to derive 
the explosion geometry and deviation from spherical symmetry, an important 
ingredient in proposed explosion models. K band can show the first overtone of 
CO, signaling the molecular formation. This will also provide a unique 
information on the dust formation in supernova, one of the proposed dust 
inventories in the Universe.