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Abundancias de isótopos de nitrógeno en el reciente viento solar
1Department of Chemistry 0317, University of California, San Diego, La Jolla 92093-0317, USA.
Nature
|June 1, 1995
Resumen
El regolito lunar contiene nitrógeno principalmente del viento solar, no de las rocas cristalinas. Nuevas mediciones revelan que este nitrógeno del viento solar tiene una proporción de 15N/14N más alta que la atmósfera de la Tierra.
Área de la Ciencia:
- Ciencias lunares y planetarias Ciencias lunares y planetarias.
- La geoquímica es la geoquímica.
- Cosmoquímica es la cosmoquímica.
Sus antecedentes:
- Las rocas cristalinas lunares son pobres en nitrógeno, mientras que las muestras de regolito muestran un contenido significativo de nitrógeno (hasta 0,012% en masa).
- El nitrógeno del regolito lunar se correlaciona con los gases nobles implantados por la radiación solar, lo que sugiere un origen solar.
- Las variaciones en la proporción de isótopos de nitrógeno (15N/14N) en muestras de regolito insinúan cambios isotópicos del viento solar a largo plazo, pero faltan mediciones directas del viento solar.
Objetivo del estudio:
- Para determinar la relación 15N/14N del viento solar contemporáneo.
- Proporcionar una firma isotópica confiable para el nitrógeno implantado en la superficie lunar durante los últimos 10^5 a 5x10^7 años.
Principales métodos:
- Análisis de isótopos de nitrógeno en dos muestras de regolito lunar con historias de exposición simples y recientes.
- Medición de la relación 15N/14N en el nitrógeno implantado.
Principales resultados:
- El nitrógeno implantado en la superficie lunar en los últimos 10^5 a 5x10^7 años exhibe una proporción de 15N/14N aproximadamente un 40% más alta que la de la atmósfera terrestre.
- Esta relación medida es sustancialmente menor que la mayoría de las estimaciones anteriores para la composición isotópica del viento solar.
Conclusiones:
- El estudio proporciona una nueva y robusta medición de la relación 15N/14N en el viento solar actual.
- Este hallazgo ayuda a explicar las variaciones isotópicas observadas en el regolito lunar y ofrece información sobre la evolución a largo plazo de la composición solar.
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