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Acreción de gas de baja metalicidad por la Vía Láctea
B P Wakker1, J C Howk, B D Savage
1Department of Astronomy, University of Wisconsin, Madison 53706, USA. wakker@astro.wisc.edu
Nature
|December 10, 1999
Resumen
Los científicos descubrieron una enorme nube de gas que cae en la Vía Láctea, con una metalicidad de 0,09 veces el valor solar. Este hallazgo apoya los modelos de evolución química galáctica y la caída continua de gas de baja metalicidad.
Área de la Ciencia:
- La astronomía galáctica es la astronomía galáctica.
- Cosmoquímica es la cosmoquímica.
- La astrofísica es la astrofísica.
Sus antecedentes:
- Los modelos de evolución química de la Vía Láctea requieren una caída continua de gas de baja metalicidad (aprox. 0.1 metalicidad solar).
- Esta caída es crucial para resolver el "problema de las enanas G" diluyendo el enriquecimiento estelar de elementos pesados y manteniendo un estrecho rango de metalicidad en las estrellas de larga vida.
- El gas de baja metalicidad crucial para la caída galáctica se ha observado escasamente en galaxias enanas y en el disco externo de la Vía Láctea, con observaciones lejanas de absorbentes amortiguados de Ly alpha.
Objetivo del estudio:
- Para investigar la metalicidad y la tasa de caída de una nube masiva de gas observada cayendo en el disco de la Vía Láctea.
- Para evaluar si la caída de gas observada se alinea con las predicciones teóricas para la evolución química galáctica.
Principales métodos:
- Análisis espectroscópico de una masiva nube de gas en caída para determinar su metalicidad.
- Estimación del caudal de masa de la nube para calcular la precipitación por unidad de área.
Principales resultados:
- Una nube masiva que cae en el disco de la Vía Láctea exhibe una metalicidad de 0,09 veces el valor solar.
- La tasa de flujo de masa de esta nube corresponde a una caída por unidad de área consistente con las expectativas teóricas.
- Esta caída observada representa aproximadamente 0.1-0.2 veces la tasa total requerida para toda la galaxia de la Vía Láctea.
Conclusiones:
- El descubrimiento de esta nube de baja metalicidad proporciona evidencia observacional directa que apoya los modelos de evolución química galáctica.
- Los hallazgos confirman la presencia y la importancia de la acumulación de gas de baja metalicidad para mantener la composición química de la Vía Láctea.
- Este estudio pone de relieve la importancia de la caída de gas en curso en la regulación de la metalicidad galáctica y la formación de estrellas.
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