(Proposal ID) S15A-078

(PI) Maeda, Keiichi

(Proposal Title)
 Connection between the Environment and Supernova Explosions

(Abstract)
We propose a follow-up program of nearby Supernovae (SNe) at late phases 
(> 150 days after the explosion), mainly targeting those with the early-phase 
high spectral resolution data available. Studies in the past few years have 
uncovered diverse/multiple populations, and our goal is to understand how they 
are related to different environment in order to clarify origins of these 
diversities. The high spectral resolution data uniquely provide properties of
 CSM/ISM around SNe, and the proposed late-time observations uniquely provide 
properties of the explosion and a measure of different populations. This is 
the first systematic study connecting the environment and the explosions/
populations using ~ 10 - 15 SNe sample. The late-time data are also powerful 
to limit the amount of CSM/ISM through the scattered light echo and to give 
an extinction measure: Connecting these with the high-resolution information 
is a powerful and unique way to deepen our understanding of the origin of the 
non-standard extinction law toward SNe Ia. Finally, we aim to obtain late-time 
optical data for extremely nearby SN Ia 2014J: This is the final piece in the 
multi-epoch and multi-frequency census for SNe, so far only rivaled by SN 1987A.