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Una composición isotópica no terrestre rica en 16O para la nebulosa protosolar
Ko Hashizume1, Marc Chaussidon
1Department of Earth and Space Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan. kohash@ess.sci.osaka-u.ac.jp
Nature
|April 1, 2005
Resumen
Los meteoritos primitivos muestran isótopos de oxígeno inusuales, lo que plantea preguntas sobre la composición del sistema solar temprano. El análisis del viento solar en los granos lunares revela un enriquecimiento significativo de 16O, lo que sugiere que ocurrieron reacciones desconocidas independientes de la masa.
Área de la Ciencia:
- Cosmoquímica es la cosmoquímica.
- Ciencias planetarias Ciencias planetarias.
- La astrofísica es la astrofísica.
Sus antecedentes:
- Los meteoritos primitivos exhiben grandes variaciones isotópicas de oxígeno inexplicables por la fraccionamiento dependiente de la masa.
- La composición del gas protosolar sigue siendo incierta debido a las limitaciones en las observaciones astronómicas.
Objetivo del estudio:
- Para determinar con precisión la composición isotópica de oxígeno del viento solar.
- Para investigar el origen de los isótopos anómalos de oxígeno en el sistema solar temprano.
Principales métodos:
- Análisis de isótopos de oxígeno en partículas de viento solar implantadas en granos metálicos del regolito lunar.
- Análisis isotópico de alta resolución de capas a escala nanométrica.
Principales resultados:
- Las partículas de viento solar en los granos lunares muestran enriquecimiento en 16O (>20 +/- 4 por mil) en comparación con la Tierra, Marte y los meteoritos.
- Este enriquecimiento implica la existencia de reacciones isotópicas independientes de masa desconocidas en el disco de acreción solar.
Conclusiones:
- La composición isotópica de oxígeno del viento solar difiere significativamente de los materiales planetarios a granel.
- Reacciones desconocidas, potencialmente involucrando auto blindaje fotoquímico, alteraron las relaciones isotópicas en el sistema solar temprano independientemente de la masa isotópica.
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