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Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx
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Relación anómala de isótopos de nitrógeno en los cometas
Claude Arpigny1, Emmanuël Jehin, Jean Manfroid
1Institut d'Astrophysique et de Géophysique, Sart-Tilman, Bâtiment B5c, B-4000 Liège, Belgium. Claude.Arpigny@ulg.ac.be
Science (New York, N.Y.)
|September 13, 2003
Resumen
Las proporciones de isótopos de nitrógeno cometarios, medidas con espectros de alta resolución, son más bajas que las de la Tierra. Esto sugiere que los cometas contienen otras fuentes de nitrógeno más allá del HCN, posiblemente compuestos orgánicos.
Área de la Ciencia:
- La astronomía y la astrofísica.
- Ciencias planetarias Ciencias planetarias.
- La espectroscopia es una técnica de espectroscopia.
Sus antecedentes:
- La composición de los cometas proporciona información sobre los inicios del Sistema Solar.
- Las relaciones isotópicas en los cometas pueden revelar su origen y evolución química.
- La molécula CN es un marcador común en el coma cometario.
Objetivo del estudio:
- Para determinar las relaciones isotópicas de carbono (12C/13C) y nitrógeno (14N/15N) en los cometas C/1995 O1 (Hale-Bopp) y C/2000 WM1 (LINEAR).
- Para investigar posibles anomalías en la composición isotópica cometaria en comparación con los valores terrestres.
- Para identificar posibles moléculas progenitoras del radical CN en los cometas.
Principales métodos:
- Espectroscopia de alta resolución de la banda B2+-X2+ (0,0) de la CN a 390 nm.
- Análisis de datos espectrales para obtener las relaciones isotópicas 12C/13C y 14N/15N.
- Comparación de las relaciones isotópicas cometarias con los estándares terrestres y otras mediciones cometarias.
Principales resultados:
- Las relaciones medidas de 12C/13C para Hale-Bopp y LINEAR fueron de 165 +/- 40 y 115 +/- 20, respectivamente.
- Las relaciones medidas de 14N/15N para Hale-Bopp y LINEAR fueron de 140 +/- 35 y 140 +/- 30, respectivamente.
- Los ratios medidos de 14N/15N son significativamente más bajos que el valor terrestre (272) y los ratios previamente reportados para Hale-Bopp de HCN.
Conclusiones:
- Las anormales proporciones isotópicas de nitrógeno sugieren que el CN en estos cometas se origina en moléculas progenitoras distintas al HCN.
- Se indica la presencia de moléculas progenitoras con proporciones aún más bajas de 14N/15N.
- Los compuestos orgánicos, potencialmente similares a los que se encuentran en las partículas de polvo interplanetario, son candidatos plausibles para estas especies madre alternativas de la CN.
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