S18A0095abst
S18A0095
We propose rapid ToO spectroscopy within 24 hrs after the discovery, for 4 nearby very young core-collapse supernovae (CCSNe) within 50 Mpc, and then follow one of these targets at another four epochs to follow the evolution, through the Gemini (N&S) rapid ToO mode. Such rapid spectroscopic data within a few days after the explosion is key to diagnosing the circumstellar (CS) environment around a progenitor star, which can be translated to the still-unclarified mass loss history of a massive star in the final years before the explosion. While such quick optical spectroscopy has opened a new time-domain window and brought many surprises in the last few years, a synergetic follow-up program coordinated with radio observation, which is the most powerful probe to the CS environment, is still missing. In S18A, the proposal team will have secured observing time in observing nearby SNe soon after the discovery in sub-mm wavelengths by ALMA, and in cm wavelengths by ATCA and GMRT. Combined with the proposed Gemini observation, it will provide the first opportunity to clarify the final evolution of massive stars in the last few years from a synoptic view point, by robustly determining the nature of the CS environment in the vicinity of SN progenitor star.
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