How much amount and what size of dust are formed in the ejecta of core-collapse 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 small-mass 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 ( uniform and power-law profiles ) for the circumstellar medium ( CSM ) .
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 _ { \odot } but the average radius of dust is smaller than 0.01 \mu m and is significantly different from those in SNe II-P with the massive hydrogen envelope ; in the explosion with the small-mass 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 form .
In addition , the low-mass hydrogen envelope of the SN IIb leads to the early arrival of the reverse shock at the dust-forming region .
If the CSM is more or less spherical , therefore , the newly formed small grains would be completely destroyed in the relatively dense shocked gas for the CSM hydrogen density of n _ { H } > 0.1 cm ^ { -3 } without being injected into the ISM .
However , the actual CSM is likely to be non-spherical , so that a part of dust grains could be ejected into the ISM without being shocked .
We demonstrate that the temporal evolution of the spectral energy distribution ( SED ) by thermal emission from dust is sensitive to the ambient gas density and structure that affects the passage of the reverse shock into the ejecta .
Thus , the SED evolution well reflects the evolution of dust through erosion by sputtering and stochastic heating .
For Cas A , we consider the CSM produced by the steady mass loss of \dot { M } \simeq 8 \times 10 ^ { -5 } M _ { \odot } yr ^ { -1 } during the supergiant phase .
Then we find that the observed infrared SED of Cas A is reasonably reproduced by thermal emission from the newly formed dust of 0.08 M _ { \odot } , which consists of the 0.008 M _ { \odot } shock-heated warm dust and 0.072 M _ { \odot } unshocked cold dust .