热计时学揭示的H-地铁母小行星的结构和热史
Mario Trieloff1, Elmar K Jessberger, Ingrid Herrwerth
1Mineralogisches Institut der Universität Heidelberg, Im Neuenheimer Feld 236, D-69120 Heidelberg, Germany. trieloff@min.uni-heidelberg.de
Nature
|April 4, 2003
概括
早期的太阳系行星体,如H地铁,可能是由于-26衰变的内部加热而迅速形成的. 这创造了层叠的母体,这些母体在数百万年内冷却,中心地区的温度更高,冷却速度比外层慢.
科学领域:
- 行星科学 行星科学
- 太空化学 太空化学
- 地质时间学 (Geochronology)
背景情况:
- 早期的太阳系在46亿年前从一个分子云中形成.
- 小行星的形成发生得很快,在1000万年内.
- 流星母体的热史和热源受到争论.
研究的目的:
- 研究H地铁母体的热史和冷却情况.
- 确定导致未分化的石转型的热源.
- 重建早期行星体的结构和冷却速度.
主要方法:
- 使用了244Pu裂变轨道热时计学.
- 雇员 40Ar-39Ar 热时间学.
- 分析了来自一个假定单亲身体的未受冲击的H地铁.
主要成果:
- 证据表明,快速积累后会有内部加热,可能来自26Al衰变.
- 母体形成了一个分层结构,具有明显的热梯度.
- 外部地区的冷却速度更快,温度低于中心地区.
- 中部地区需要大约1.6亿年才能冷却到390K.
结论:
- 合金形的热源可能是26Al衰变.
- 积聚和分化是太阳系早期的快速过程.
- 冷却历史表明,一个分层的母体结构在长时间内冷却.
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