Asymmetries in core-collapse supernovae from maps of radioactive 44Ti in Cassiopeia A.
Nature
; 506(7488): 339-42, 2014 Feb 20.
Article
em En
| MEDLINE
| ID: mdl-24553239
ABSTRACT
Asymmetry is required by most numerical simulations of stellar core-collapse explosions, but the form it takes differs significantly among models. The spatial distribution of radioactive (44)Ti, synthesized in an exploding star near the boundary between material falling back onto the collapsing core and that ejected into the surrounding medium, directly probes the explosion asymmetries. Cassiopeia A is a young, nearby, core-collapse remnant from which (44)Ti emission has previously been detected but not imaged. Asymmetries in the explosion have been indirectly inferred from a high ratio of observed (44)Ti emission to estimated (56)Ni emission, from optical light echoes, and from jet-like features seen in the X-ray and optical ejecta. Here we report spatial maps and spectral properties of the (44)Ti in Cassiopeia A. This may explain the unexpected lack of correlation between the (44)Ti and iron X-ray emission, the latter being visible only in shock-heated material. The observed spatial distribution rules out symmetric explosions even with a high level of convective mixing, as well as highly asymmetric bipolar explosions resulting from a fast-rotating progenitor. Instead, these observations provide strong evidence for the development of low-mode convective instabilities in core-collapse supernovae.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Nature
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Estados Unidos