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Observación del isótopo de reloj de nucleosíntesis 60Fe en los rayos cósmicos galácticos
W R Binns1, M H Israel1, E R Christian2
1Washington University, St. Louis, MO 63130, USA. wrb@wustl.edu mhi@wustl.edu.
Science (New York, N.Y.)
|April 23, 2016
Resumen
El hierro radiactivo-60 ((60) Fe) detectado en los rayos cósmicos proporciona un reloj para la fecha de los eventos cósmicos. Su presencia sugiere que las supernovas ocurrieron cerca y recientemente, hace 1 kiloparsec y 2,6 millones de años.
Área de la Ciencia:
- Física de los rayos cósmicos
- La astrofísica nuclear
- Datamiento por isótopos radiactivos
Sus antecedentes:
- El hierro-60 ((60) Fe) es un isótopo radiactivo encontrado en los rayos cósmicos.
- Actúa como un reloj cósmico, ayudando a determinar el tiempo entre la nucleosíntesis y la aceleración de partículas.
- Comprender el origen y el transporte de (60) Fe proporciona información sobre eventos astrofísicos como las supernovas.
Objetivo del estudio:
- Para detectar y cuantificar el hierro-60 ((60) Fe) en los rayos cósmicos.
- Utilizar el (60) Fe detectado para inferir restricciones en el tiempo entre la nucleosíntesis y la aceleración.
- Estimar la distancia a la fuente de (60) Fe y su mecanismo de producción.
Principales métodos:
- Utilizó el instrumento ACE-CRIS para recolectar aproximadamente 3.55 × 10 ^ 5 núcleos de hierro.
- Núcleos de hierro analizados dentro del rango de energía de ~ 195 a ~ 500 megaelectronvoltios por nucleón.
- Se identificaron 15 (60) núcleos de Fe entre las muestras de hierro recogidas.
Principales resultados:
- Se identificaron 15 (60) núcleos de Fe de una muestra de 3,55 × 10^5 núcleos de hierro.
- Se determinó una relación de fuente de (60) Fe / (56) Fe para ser (7,5 ± 2,9) × 10^-5.
- Los hallazgos implican que el tiempo de aceleración y transporte a la Tierra es menor que la vida media de 2,6 millones de años del (60) Fe.
Conclusiones:
- La detección de supernova producida (60) Fe en los rayos cósmicos sugiere orígenes cercanos.
- La distancia a la fuente está limitada a menos de aproximadamente 1 kiloparsec.
- Los cúmulos estelares masivos cercanos son un origen plausible para el (60) Fe detectado.
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