Inhomogeneous stellar mixing in the final hours before the Cassiopeia A supernova
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866913935967387648 |
|---|---|
| author | Sato, Toshiki Matsunaga, Kai Uchida, Hiroyuki Katsuda, Satoru Takahashi, Koh Umeda, Hideyuki Takiwaki, Tomoya Sawada, Ryo Yoshida, Takashi Nakamura, Ko Kuboike, Yui Plucinsky, Paul P. Hughes, John P. |
| author_facet | Sato, Toshiki Matsunaga, Kai Uchida, Hiroyuki Katsuda, Satoru Takahashi, Koh Umeda, Hideyuki Takiwaki, Tomoya Sawada, Ryo Yoshida, Takashi Nakamura, Ko Kuboike, Yui Plucinsky, Paul P. Hughes, John P. |
| contents | Understanding stars and their evolution is a key goal of astronomical research and has long been a focus of human interest. In recent years, theorists have paid much attention to the final interior processes within massive stars, as they can be essential for revealing neutrino-driven supernova mechanisms and other potential transients of massive star collapse. However, it is challenging to observe directly the last hours of a massive star before explosion, since it is the supernova event that triggers the start of intense observational study. Here we report evidence for a final phase of stellar activity known as a ``shell merger'', an intense shell burning in which the O-burning shell swallows its outer C-/Ne-burning shell, deep within the progenitor's interior moments before the supernova explosion. In the violent convective layer created by the shell merger, Ne, which is abundant in the stellar O-rich layer, is burned as it is pulled inward, and Si, which is synthesized inside, is transported outward. The remnant still preserves some traces of such Ne-rich downflows and Si-rich upflows in the O-rich layer, suggesting that inhomogeneous shell-merger mixing began just hours ($\lesssim 10^4$ s) before its gravitational collapse. Our results provide the first observational evidence that the final stellar burning process rapidly alters the internal structure, leaving a pre-supernova asymmetry. This breaking of spherical symmetry facilitates the explosion of massive stars and influences various supernova and remnant characteristics, including explosion asymmetries and the neutron star's kick and spin. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_07563 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Inhomogeneous stellar mixing in the final hours before the Cassiopeia A supernova Sato, Toshiki Matsunaga, Kai Uchida, Hiroyuki Katsuda, Satoru Takahashi, Koh Umeda, Hideyuki Takiwaki, Tomoya Sawada, Ryo Yoshida, Takashi Nakamura, Ko Kuboike, Yui Plucinsky, Paul P. Hughes, John P. High Energy Astrophysical Phenomena Understanding stars and their evolution is a key goal of astronomical research and has long been a focus of human interest. In recent years, theorists have paid much attention to the final interior processes within massive stars, as they can be essential for revealing neutrino-driven supernova mechanisms and other potential transients of massive star collapse. However, it is challenging to observe directly the last hours of a massive star before explosion, since it is the supernova event that triggers the start of intense observational study. Here we report evidence for a final phase of stellar activity known as a ``shell merger'', an intense shell burning in which the O-burning shell swallows its outer C-/Ne-burning shell, deep within the progenitor's interior moments before the supernova explosion. In the violent convective layer created by the shell merger, Ne, which is abundant in the stellar O-rich layer, is burned as it is pulled inward, and Si, which is synthesized inside, is transported outward. The remnant still preserves some traces of such Ne-rich downflows and Si-rich upflows in the O-rich layer, suggesting that inhomogeneous shell-merger mixing began just hours ($\lesssim 10^4$ s) before its gravitational collapse. Our results provide the first observational evidence that the final stellar burning process rapidly alters the internal structure, leaving a pre-supernova asymmetry. This breaking of spherical symmetry facilitates the explosion of massive stars and influences various supernova and remnant characteristics, including explosion asymmetries and the neutron star's kick and spin. |
| title | Inhomogeneous stellar mixing in the final hours before the Cassiopeia A supernova |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2507.07563 |