タイトル：Type Ia Supernova triggered by Helium detonation
アブスト：Type Ia Supernovae (SNe) show diversity in the observational properties. The different sub classes may well represent different progenitor evolutions and explosion modes. However, so far there is no direct and robust link developed to any particular theoretical model to real observed samples. Recently, we detected a very young SN Ia soon after the explosion using Subaru/HSC. This new information (emission within a day) as linked to its peculiar spectra around maximum light led us to conclude that this SN was triggered by the He detonation on the surface of the white dwarf. This is the first example for which we can robustly identify the explosion mechanism for an SN Ia.