S20B0056abst

S20B0056

We propose late-time spectroscopy of ∼6 supernovae (SNe) by Subaru/FOCAS, aiming at connecting the properties of SNe soon after the explosion (in the first few days, by Seimei telescope) to the late phases (150 - 300 days, by Subaru/FOCAS). The earliest-phase data are sensitive to the properties of the outermost ejecta and the closest circum-stellar media (CSM), while the late-phase data provide totally different diagnostics on the nature of the progenitor and the CSM in a larger scale. As the Seimei and Tomo-e have started operation, it is time to connect these different diagnosing observations and seek for a unified picture of these stellar explosions. Our goal is to identify an origin of the massive star activity in the final few years, while we can also study origins of enigmatic transients.

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