Abstract Details
| Name: Dipang Vaishnav Affiliation: St. Joseph's University Conference ID: ASI2025_424 Title : Spectroscopic Study of Type-II Supernovae in Progenitors with Extended H-envelope Authors and Co-Authors : DIANA JOSE 1, DIPANG VAISHNAV 1, JUANITA EARLYN ANDREW 1, FIROZA SUTARIA 2, ALAK RAY 3 Abstract Type : Poster Abstract Category : Stars, Interstellar Medium, and Astrochemistry in Milky Way Abstract : Type-II supernovae in progenitors with an extended H-envelope follow a light curve with three distinctive phases: (a) an initial cooling peak (b) a recombination plateau, as the ionized hydrogen recombines, and finally, as the event enters the nebular phase, (c) a long tail fueled by radioactive decay of 56Ni → 56Co → 56Fe. We present here a spectroscopic study of three type II events– the radiobright SN2018ivc, SN2024exw and SN2024ggi– observed at similar epochs. The early spectra reveal prominent emission lines, including Hα, Hβ, Hγ, Hδ, Hϵ, He I, C IV, and Fe I, II, and III, and absorption features of Na I, all with varying intensities as the SNe evolves. In the late nebular stage, the Ca II and [Ca II] NIR lines and other metal lines also emerge. We present a detailed analysis of the Balmer line profiles, notably Hα, which retain their characteristic P-Cygni structure well into the nebular phase. We use our spectral studies to characterize the progenitor’s and its environment’s properties (e.g. mass, local metallicity, etc.), and to quantify the dynamics of shock-ejecta interactions as a function of the progenitor characteristics. Key words: Type-II SNe, H-envelope, SN2018ivc, SN2024exw, SN2024ggi, P-Cygni , mass, metallicity |