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Recientes supernovas cercanas a la Tierra sondeadas por deposición global de radioactivo interestelar (60) Fe

A Wallner¹, J Feige², N Kinoshita³

¹Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University (ANU), Canberra, Australian Capital Territory 2601, Australia.

|April 15, 2016

Resumen

Las supernovas cerca de la Tierra son raras, ocurriendo cada 2-4 millones de años. El análisis de los archivos de aguas profundas revela evidencia de hierro interestelar-60 (60Fe) de múltiples eventos de supernovas pasadas.

Área de la Ciencia:

Astronomía y astrofísica
Los rayos cósmicos y la física de partículas
Geoquímica

Sus antecedentes:

Las supernovas y los vientos de estrellas masivas expulsan radionúclidos como el hierro-60 (60Fe) al espacio interestelar.
Estos radionúclidos, con largas vidas medias, pueden conservarse en granos de polvo interestelar.
Tal polvo, si entra en el Sistema Solar, puede proporcionar un registro de la actividad estelar pasada.

Objetivo del estudio:

Investigar el origen y la extensión de la señal de hierro-60 (60Fe) encontrada en las costras de aguas profundas.
Para determinar si la señal de 60Fe es global, extendida en el tiempo y de origen interestelar.
Para reconstruir la historia de los eventos de estrellas masivas y supernovas cercanas.

Principales métodos:

Análisis de núcleos de sedimentos de aguas profundas de todos los grandes océanos para detectar la deposición de 60Fe.
Datación radiométrica de las capas de sedimento para establecer líneas de tiempo de la afluencia de 60Fe.
Comparación de los patrones de deposición de 60Fe con las tasas y distancias de supernova conocidas.

Principales resultados:

La señal de 60Fe en los archivos de aguas profundas está confirmada como global y de origen interestelar.
Se detectaron influjos significativos de 60Fe correspondientes a intervalos de tiempo de hace 1.5-3.2 millones de años y hace 6.5-8.7 millones de años.
Los hallazgos implican que un pequeño porcentaje del 60Fe expulsado fue capturado por el polvo y depositado en la Tierra.

Conclusiones:

Múltiples eventos de supernovas y estrellas masivas han ocurrido dentro de los 100 parsecs de la Tierra en los últimos diez millones de años.
El registro de 60Fe proporciona evidencia directa de recientes fenómenos estelares energéticos cercanos.
Este estudio mejora nuestra comprensión de la frecuencia y el impacto de las supernovas en las cercanías del Sistema Solar.

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