He Abundance of Dense Circumstellar Clumps in the Cassiopeia A Supernova Remnant

We report on the result of He abundance analysis of dense circumstellar clumps in the young supernova remnant Cassiopeia A. These clumps, which are called quasi-sta tionary flocculi (QSFs), are known from previous optical studies to be enriched in He along with N, but the degree of He overabundance...

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Veröffentlicht in:The Astrophysical journal 2023-03, Vol.945 (2), p.158
Hauptverfasser: Koo, Bon-Chul, Kim, Dongkok, Yoon, Sung-Chul, Raymond, John C.
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Sprache:eng
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Zusammenfassung:We report on the result of He abundance analysis of dense circumstellar clumps in the young supernova remnant Cassiopeia A. These clumps, which are called quasi-sta tionary flocculi (QSFs), are known from previous optical studies to be enriched in He along with N, but the degree of He overabundance relative to H has remained uncertain. For several QSFs with near-infrared spectroscopic data, we have analyzed their He i 1.083 μ m/Pa γ ratios together with the ratios of [Fe ii ] lines by using the Raymond shock code. According to our analysis, He is overabundant relative to H by a factor of ≲3 in most of these QSFs. This He abundance of QSFs is consistent with the previous conclusion from the N overabundance that QSFs were ejected when a substantial amount of the H envelope of the progenitor star had been stripped off. We discuss the mass-loss history of the progenitor star and the origin of QSFs.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/acb7e7