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Tecnecio extinto en granos de polvo estelar de carburo de silicio: implicaciones para la nucleosíntesis estelar

Michael R Savina¹, Andrew M Davis, C Emil Tripa

¹Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA. msavina@anl.gov

Science (New York, N.Y.)

|January 31, 2004

Resumen

Los granos de polvo estelar de carburo de silicio presolar revelan las firmas de la nucleosíntesis del proceso s. Una anomalía en el rutenio-99 (99Ru) apunta a la desintegración del tecnecio-99 (99Tc), lo que indica orígenes de estrellas gigantes ramificadas asimptóticas de baja masa.

Área de la Ciencia:

Análisis del polvo cósmico.
La nucleosíntesis estelar.
La geoquímica isotópica es una de ellas.

Sus antecedentes:

Los granos presolares de carburo de silicio (SiC) son restos de estrellas anteriores a la formación del Sistema Solar.
Su composición isotópica proporciona información sobre los procesos de nucleosíntesis estelar.

Objetivo del estudio:

Para investigar el origen de los granos de SiC presolar utilizando anomalías isotópicas de rutenio (Ru).
Comprender la contribución de las estrellas de ramas gigantes asimptóticas (AGB) a la composición del grano presolar.

Principales métodos:

Análisis de la composición isotópica del rutenio (Ru) en granos individuales de polvo estelar presolar de SiC.
Comparación de las anomalías isotópicas observadas con los modelos teóricos de nucleosíntesis y decaimiento radiactivo.

Principales resultados:

La firma isotópica de Ru en los granos de SiC presolar coincide con la nucleosíntesis del proceso s en las estrellas AGB.
Una anomalía específica en 99Ru se atribuye a la desintegración in situ del tecnecio-99 (99Tc) dentro de los granos.
La abundancia de 99Tc producida en estrellas AGB de baja masa es insuficiente para explicar una anomalía de 99Ru detectable en los primeros materiales del sistema solar.

Conclusiones:

La mayoría de los granos de SiC presolar se originan en estrellas gigantes asintóticas de baja masa.
La anomalía de 99Ru observada en los granos presolares es el resultado de la desintegración de 99Tc dentro de los granos.
La producción de 99Tc en estas estrellas es limitada, lo que afecta el registro isotópico del Sistema Solar temprano.

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