(Proposal ID) S12B-064

(PI) Maeda, Keiichi

(Proposal Title)
Late-Time NIR Properties of Supernovae: Further Diversities?

(Abstract)
We propose to take J & H band spectra and photometry for a few nearby 
Supernovae (SNe) at late phases such as ~ 150 - 200 days after the explosion. 
We expect to have a few Type Ia SNe (SNe Ia) in one semester, which can be 
targets of ToO mode using IRCS and LGS-AO. Late-time spectra can be used to 
probe distributions of different elements/isotopes, thus providing so far the 
only tool to tackle how the thermonuclear ignition starts. The same applies to 
core-collapse SNe, although rare for our observational set up, which will be 
useful to constrain the nature of the explosion. The investigation, however, 
has been restricted to optical wavelength. NIR late-time spectroscopy is more 
challenging, but provides much more detailed information. In the wavelength 
range near [Fe II] J & H, there are virtually no contamination from other 
lines, allowing the detailed line profiles being investigated. This provides 
the distributions of stable Fe-peak elements and radioactive ^56Ni separately, 
and thus the detailed nature on ignition process. This will allow to 
investigate a relation between the detailed explosion mechanism and the 
standard-candle-natures of SNe Ia, with qualitatively different information 
from those previously obtained by conventional SN observations.