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Impresiones de estrellas masivas que giran rápidamente en el Bulge Galáctico
Cristina Chiappini1, Urs Frischknecht, Georges Meynet
1Astrophysikalisches Institut Potsdam, An der Sternwarte 16, Potsdam, 14482, Germany. cristina.chiappini@aip.de
Nature
|April 29, 2011
Resumen
Las primeras estrellas enriquecieron el universo con elementos pesados. El análisis de estrellas antiguas revela abundancias inusuales de elementos, lo que sugiere un nuevo modelo para la nucleosíntesis estelar temprana que involucra estrellas masivas de rotación rápida.
Área de la Ciencia:
- La astronomía y la astrofísica.
- Evolución Estelar Evolución Estelar
- Cosmoquímica es la cosmoquímica.
Sus antecedentes:
- El Universo primitivo estaba compuesto principalmente de hidrógeno y helio.
- Se cree que las estrellas masivas producen los primeros elementos pesados ("metales").
- Los cúmulos globulares contienen algunas de las estrellas más antiguas, preservando la historia química galáctica temprana.
Objetivo del estudio:
- Investigar la composición química de las estrellas en el antiguo cúmulo globular NGC 6522.
- Resolver la aparente contradicción entre las abundancias esperadas de elementos pesados de estrellas masivas y las abundancias observadas en estrellas antiguas.
- Pruebe la hipótesis de que las estrellas masivas de rotación rápida y pobres en metales pueden explicar los patrones elementales observados.
Principales métodos:
- Reanálisis de los datos espectrales existentes de ocho estrellas en NGC 6522.
- Análisis detallado de la abundancia de elementos, incluidos los elementos alfa, el europio (Eu), el bario (Ba), el lantano (La), el ittrio (Y), el estroncio (Sr) y el carbono (C).
- Comparación de las abundancias observadas con las predicciones de los modelos de nucleosíntesis estelar.
Principales resultados:
- Las estrellas en NGC 6522 muestran altas proporciones de alfa-elemento/Fe y Eu/Fe, consistentes con el enriquecimiento por estrellas masivas.
- Estas estrellas exhiben abundancias anormalmente altas de Ba y La en relación con el hierro.
- El nuevo análisis confirmó sobreabundancias de Y y Sr con dispersión significativa, mientras que las abundancias de carbono no se mejoraron.
Conclusiones:
- Los patrones de abundancia observados, particularmente el alto Ba, La, Y y Sr, se explican mejor por la nucleosíntesis en estrellas masivas de rotación rápida y pobres en metales.
- Este hallazgo apoya los modelos teóricos que mejoran la producción de elementos de captura lenta de neutrones (proceso s) en estas estrellas.
- Los resultados sugieren que las estrellas masivas de rotación rápida y pobres en metales pueden haber sido una fuente común y significativa de elementos del proceso s en el Universo temprano, lo que potencialmente caracteriza las primeras generaciones estelares.
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