(Proposal ID) S14A-189 (PI) Yamanaka Masayuki (Proposal Title) Constraining Progenitors of Type Ia Supernovae from Late-Time Spectra (Abstract) We propose a follow-up program of Type Ia Supernovae (SNe Ia) at late phases (>150 days after the explosion), using FOCAS and IRCS/AO. In the last few years, a new picture about the SNe Ia progenitor(s) has been emerging - some of them are from a pair of a white dwarf (WD) and a non-degenerate star while others from a WD-WD pair. However, it has not been clarified which individual SNe Ia are from either of the systems. There are a few suggestinos to probe the progenitor for individual SNe Ia, (1) photometry within a week after the explosion, and (2) spectroscopy in late phases. There is only one SN Ia for which both methods have been applied. In this proposal, we aim to apply the two independent methods for 4 SNe Ia for which we have obtained extensive data since very early within a week after the explosion (2 SNe Ia within a day or two), with the FOCAS late-phase spectra. For one of these SNe Ia, we aim to obtain a deep late-time NIR spectrum, which provides the best case to study the progenitor and explosion properties using various methods available in optical and NIR. Further, we aim to observe a few other peculiar SNe Ia in the late-phase by FOCAS. These will provide a unique data set to address the relation between the progenitor and the SN diversity.