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Muestras de estrellas más allá del sistema solar: granos de silicato en el polvo interplanetario
Scott Messenger1, Lindsay P Keller, Frank J Stadermann
1Laboratory for Space Sciences and Physics Department, Washington University, St. Louis, MO 63130, USA.
Science (New York, N.Y.)
|March 1, 2003
Resumen
Seis granos de silicato extraterrestres encontrados en partículas de polvo interplanetario (IDP) proporcionan pistas sobre los orígenes estelares. Estas composiciones isotópicas anómalas sugieren orígenes cometarios para los PDI, en contraste con el polvo de meteoritos.
Área de la Ciencia:
- Análisis del polvo cósmico Análisis del polvo cósmico
- La geoquímica isotópica es una geoquímica isotópica.
- Evolución estelar y nucleosíntesis estelar.
Sus antecedentes:
- Las partículas de polvo interplanetario (IDP) son cruciales para comprender la transferencia de material dentro del sistema solar.
- Los granos de polvo circumestelar, originados en estrellas evolucionadas, llevan las firmas isotópicas de sus estrellas progenitoras.
- Estudios anteriores observaron una discrepancia en los tipos de polvo circumestelar que se encuentran en los meteoritos frente a los IDP.
Objetivo del estudio:
- Para identificar y caracterizar los granos de silicato circunstelar dentro de los PDI.
- Para determinar los orígenes estelares de estos granos utilizando composiciones isotópicas de oxígeno.
- Investigar las implicaciones para la formación y la entrega de IDP y la naturaleza del polvo circumestelar.
Principales métodos:
- Análisis microscópico e isotópico de seis granos de silicato aislados de partículas de polvo interplanetario.
- Mediciones de la relación de isótopos de oxígeno (17O/16O y 18O/16O) para identificar los orígenes extrasolares.
- Comparación de la mineralogía de los granos (forsterita, silicatos amorfos GEMS) con las observaciones astronómicas de las estrellas evolucionadas.
Principales resultados:
- Se identificaron seis granos circumestelares de silicato con composiciones isotópicas de oxígeno altamente anómalas en los PDI.
- Tres granos ricos en 17O sugieren orígenes de gigantes rojas o estrellas gigantes asintóticas.
- Un grano rico en 16O puede provenir de una estrella pobre en metales; dos granos pobres en 16O tienen fuentes estelares indeterminadas.
Conclusiones:
- La presencia de estos diversos silicatos circumestelares en los IDPs apoya un origen cometario para estas partículas.
- Este hallazgo pone de relieve una diferencia significativa entre las poblaciones de polvo en los PDI y los meteoritos.
- El estudio subraya la necesidad de realizar más investigaciones sobre la enigmática ausencia de tales silicatos en muestras de meteoritos.
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