Formation and Evolution of Dust in Type IIb Supernova with Application to the Cassiopeia A Supernova Remnant

How much amount and what size of dust are formed in the ejecta of corecollapse supernovae (CCSNe) and are injected into the interstellar medium (ISM) depend on the type of CCSNe through the thickness of outer envelope. Recently Cas A was identified as a Type IIb SN (SN IIb) that is characterized by the thin hydrogen envelope. In order to clarify how the amount of dust formed in the ejecta and supplied into the ISM depends on the type of CCSNe, we investigate the formation of dust grains in the ejecta of a SN IIb and their evolution in the shocked gas in the SN remnant (SNR) by considering two sets of density structures for the circumstellar medium (CSM); uniform and power-law density profiles. Based on these calculations, we also simulate the time evolution of thermal emission from the shock-heated dust in the SNR and compare the results with the observations of Cas A SNR. We find that the total mass of dust formed in the ejecta of a SN IIb is as large as 0.167 M⊙ but the average radius of dust smaller than 0.01 μm is significantly different from those in SNe II-P with the thick hydrogen envelope. In the explosion with the thin hydrogen envelope, the expanding He core undergoes little deceleration, so that the gas density in the He core is too low for large-sized grains to be produced. In addition, the Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 2778568, Japan; [email protected] Department of Cosmosciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan Department of Physics, Faculty of Science and Engineering, Konan University, Okamoto, Kobe 658-8501, Japan Department of Astronomy, School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany