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Mezcla profunda de 3He: reconciliando el Big Bang y la nucleosíntesis estelar
Peter P Eggleton1, David S P Dearborn, John C Lattanzio
1Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94551, USA. ppe@igpp.ucllnl.org
Science (New York, N.Y.)
|October 28, 2006
Resumen
Las estrellas de baja masa producen demasiado helio-3 (3He), lo que desafía los modelos de abundancia cósmica. Nuevas simulaciones 3D revelan una mezcla inesperada en el interior estelar, resolviendo esta discrepancia y protegiendo las predicciones de nucleosíntesis del Big Bang.
Área de la Ciencia:
- * Astrofísica es la astrofísica.
- * Evolución estelar de las estrellas.
- * La astrofísica nuclear es una astrofísica.
Sus antecedentes:
- * Las estrellas de baja masa (1-2 masas solares) son eficientes productores de helio-3 (3He).
- * La abundancia cósmica observada de 3He es menor de lo predicho por los modelos estelares y de nucleosíntesis del Big Bang.
- * Se pensaba que la pérdida de la envolvente estelar distribuía el 3He en la Galaxia, exacerbando la discrepancia de abundancia.
Objetivo del estudio:
- * Para investigar la discrepancia entre la abundancia de helio-3 (3He) cósmico predicho y observado.
- * Para modelar los procesos internos de mezcla en estrellas gigantes rojas de baja masa.
- * Para determinar si la nucleosíntesis estelar de 3He amenaza los modelos de nucleosíntesis del Big Bang.
Principales métodos:
- * Empleó un código hidrodinámico totalmente tridimensional para el modelado estelar.
- * Utilizó una red nucleosintética completa para rastrear los productos de reacción.
- * Analizó la zona radiativa entre el caparazón de combustión de hidrógeno y la envoltura convectiva.
Principales resultados:
- * Se descubrió una mezcla significativa en la zona radiativa supuestamente estable por encima de la cubierta de combustión de hidrógeno.
- * Identificó la inestabilidad de Rayleigh-Taylor como el mecanismo que impulsa esta mezcla interna.
- * Se ha demostrado que esta mezcla se produce en una región donde las reacciones nucleares reducen el peso molecular medio.
Conclusiones:
- * El recién identificado mecanismo de mezcla interna en estrellas de baja masa concilia las abundancias previstas y observadas de helio-3 (3He).
- * Este hallazgo resuelve el desafío planteado por la producción estelar de 3He a las observaciones de abundancia cósmica.
- * El estudio salvaguarda las predicciones de la nucleosíntesis del Big Bang para el helio-3 (3He).
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