Isotopic ratios for C, N, Si, Al, and Ti in C-rich presolar grains from massive stars
Abstract
Certain types of silicon carbide (SiC) grains, e.g. SiC-X grains, and low density (LD) graphites are C-rich presolar grains that are thought to have condensed in the ejecta of core-collapse supernovae (CCSNe). In this work, we compare C, N, Al, Si, and Ti isotopic abundances measured in presolar grains with the predictions of 21 CCSN models. The impact of a range of SN explosion energies is considered, with the high energy models favouring the formation of a C/Si zone enriched in 12C, 28Si, and 44Ti. Eighteen of the 21 models have H ingested into the He-shell and different abundances of H remaining from such H-ingestion. CCSN models with intermediate to low energy (that do not develop a C/Si zone) cannot reproduce the 28Si and 44Ti isotopic abundances in grains without assuming mixing with O-rich CCSN ejecta. The most 28Si-rich grains are reproduced by energetic models when material from the C/Si zone is mixed with surrounding C-rich material, and the observed trends of the 44Ti/48Ti and 49Ti/48Ti ratios are consistent with the C-rich C/Si zone. For the models with H-ingestion, high and intermediate explosion energies allow the production of enough 26Al to reproduce the 26Al/27Al measurements of most SiC-X and LD graphites. In both cases, the highest 26Al/27Al ratio is obtained with H still present at XH ≈ 0.0024 in He-shell material when the SN shock is passing. The existence of H in the former convective He-shell points to late H-ingestion events in the last days before massive stars explode as a supernova.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 2022
- DOI:
- 10.1093/mnras/stac2498
- arXiv:
- arXiv:2212.06846
- Bibcode:
- 2022MNRAS.517.1803S
- Keywords:
-
- nuclear reactions;
- nucleosynthesis;
- abundances;
- stars: abundances;
- stars: evolution;
- stars: massive;
- supernovae: general;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Monthly Notices of the Royal Astronomical Society, 517(2), pp 1803 1820 (2022)