彗星中的异常同位素比率异常
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
概括
彗星的同位素比率,用高分辨率光谱测量,低于地球的. 这表明彗星除了HCN之外还含有其他源,可能是有机化合物.
科学领域:
- 天文学和天体物理学
- 行星科学 行星科学
- 频谱学是一种光谱学.
背景情况:
- 彗星的组成提供了对早期太阳系的洞察力.
- 彗星中的同位素比可以揭示它们的起源和化学演变.
- 该CN分子是彗星昏迷中的常见标记物.
研究的目的:
- 为了确定彗星C/1995 O1 (海尔波普) 和C/2000 WM1 (LINEAR) 中的碳 (12C/13C) 和 (14N/15N) 的同位素比.
- 为了调查彗星同位素组成的潜在异常与地球价值相比.
- 为了确定彗星中CN基的可能母分子.
主要方法:
- 在390 nm的CN B2+-X2+ (0,0) 波段的高分辨率光谱.
- 分析光谱数据以获得12C/13C和14N/15N同位素比率.
- 彗星同位素比率与地球标准和其他彗星测量结果的比较.
主要成果:
- 哈雷波普和LINEAR测量的12C/13C比分分别为165 +/- 40和115 +/- 20.
- 哈雷波普和LINEAR测量的14N/15N比分分别为140 +/- 35和140 +/- 30.
- 测量到的14N/15N比率明显低于陆地价值 (272) 和之前报告的HCN的Hale-Bopp比率.
结论:
- 异常的同位素比率表明,这些彗星中的CN起源于HCN以外的母分子.
- 显示出具有更低14N/15N比率的母分子的存在.
- 有机化合物,可能与行星间尘埃颗粒中发现的有机化合物相似,是这些替代CN母物种的可信候选物.
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