太阳系之外的恒星样本:行星间尘埃中的酸盐粒
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
概括
在行星间尘埃颗粒 (IDP) 中发现的六颗外星酸盐颗粒为恒星起源提供了线索. 这些异常的同位素组成表明IDP的彗星起源,与石尘埃形成鲜明对比.
科学领域:
- 宇宙尘埃分析 太空尘埃分析
- 同位素地球化学 同位素地球化学
- 恒星进化和核合成
背景情况:
- 星际尘埃粒子 (IDP) 对于理解太阳系内的物质转移至关重要.
- 环恒星尘埃颗粒,起源于进化的恒星,携带它们母恒星的同位素签名.
- 之前的研究指出,石与内部石中发现的环恒星尘埃类型存在差异.
研究的目的:
- 在IDP中识别和描述环恒星酸盐颗粒.
- 用氧同位素组成来确定这些颗粒的恒星起源.
- 调查对内流层的形成和传递以及环恒星尘埃的性质的影响.
主要方法:
- 从行星间尘埃颗粒中分离出来的六个酸盐颗粒的微观和同位素分析.
- 测量氧同位素比率 (17O/16O和18O/16O) 以确定太阳系外的来源.
- 谷物矿物学 (森林石,无形酸盐GEMS) 与天文观测进化恒星的比较.
主要成果:
- 在IDP中确定了6个具有高度异常的氧同位素组成的环恒星酸盐粒.
- 富含17O的三粒粒表明它们起源于红巨星或非对称巨星的分支恒星.
- 一个富含16O的颗粒可能起源于一个金属贫乏的恒星;两个富含16O的颗粒有未确定的恒星来源.
结论:
- 这些多样化的环恒星酸盐在IDP中的存在支持这些粒子的彗星起源.
- 这一发现突出了内流层中的尘埃和石中的尘埃数量之间的显著差异.
- 这项研究强调了对石样本中这种酸盐神秘缺失的进一步研究的需要.
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