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La heterogeneidad de la nebulosa solar en el proceso p de los isótopos de samario y neodimio
Rasmus Andreasen1, Mukul Sharma
1Radiogenic Isotope Geochemistry Laboratory, Department of Earth Sciences, Dartmouth College, 6105 Sherman Fairchild Hall, Hanover, NH 03755, USA.
Science (New York, N.Y.)
|October 7, 2006
Resumen
Las condritas carbonáceas muestran un déficit de samario-144 (144Sm), lo que indica su distribución heterogénea en la nebulosa solar temprana. Esto sugiere fuentes de supernova distintas para los elementos de proceso p y proceso r.
Área de la Ciencia:
- Cosmoquímica es la cosmoquímica.
- La astrofísica nuclear es una astrofísica nuclear.
- Ciencias planetarias Ciencias planetarias.
Sus antecedentes:
- Las condritas carbonáceas a granel exhiben un déficit notable en 144Sm (aprox. 100 ppm) en comparación con otros meteoritos y estándares terrestres.
- Este déficit se correlaciona con una disminución de los ratios 142Nd/144Nd en aproximadamente. 11 partes por millón en estos meteoritos.
Objetivo del estudio:
- Para investigar las anomalías isotópicas en el samario (Sm) y el neodimio (Nd) dentro de las condritas carbonáceas.
- Determinar los patrones de distribución de los isótopos Sm y Nd originados por diferentes procesos de nucleosíntesis en la nebulosa solar temprana.
Principales métodos:
- Análisis isotópico de samario y neodimio en condritas carbonáceas a granel.
- Comparación de las relaciones isotópicas con los estándares terrestres y de otros meteoritos.
- Modelado de la heterogeneidad isotópica basada en orígenes nucleosintéticos (proceso p, proceso r, proceso s).
Principales resultados:
- Se confirmó un déficit significativo en 144Sm y una disminución correspondiente en las proporciones de 142Nd/144Nd en las condritas carbonáceas.
- Los isótopos producidos por el proceso p en las supernovas se distribuyeron de manera heterogénea en la nebulosa solar.
- Se encontró que los isótopos producidos por el proceso r (supernovas) y el proceso s (gigantes rojas) se distribuyen de manera homogénea.
Conclusiones:
- La distribución heterogénea de los isótopos Sm y Nd del proceso p implica fuentes de supernovas distintas o débilmente conectadas para estos núcleos.
- La distribución homogénea de los isótopos del proceso r y el proceso s sugiere una mezcla más uniforme de estos elementos de sus respectivas fuentes.
- Esta evidencia isotópica limita los sitios astrofísicos y los procesos de mezcla responsables de la composición elemental de la nebulosa solar temprana.
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