Condensation of major and trace elements in dust-rich environments

IF 3 2区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Icarus Pub Date : 2025-09-15 DOI:10.1016/j.icarus.2025.116801

Marwane Mokhtari, Bernard Bourdon

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引用次数: 0

Abstract

Recent astronomical observations have shown that dust can get locally concentrated in protoplanetary disks, forming ring structures. The thermal processing of such regions could lead to dust evaporation and local enrichment of the solar gas in condensable elements. Previous studies focusing on major element behavior have shown that condensation of such dust-enriched gas could lead to the formation of a silicate melt with compositions resembling that of chondrules. However, previous studies focusing on dust-enriched environments were restricted to a limited set of elements. To study the mineralogical and chemical composition of condensates in these conditions, we have performed equilibrium calculations using the FactSage™ software for a dust-enriched solar gas. The calculations were done with dust-enrichment factors of 1 (solar composition), 10 and 100 at pressures ranging between 10⁻⁶ bar and 10⁻³ bar, for a CI-chondrite dust and a H-chondrite dust. The trace element condensation was accurately modelled with newly calculated activity coefficients in different solid and melt solutions. The available gas phase database was completed with new trace element species that are important to consider in oxidized conditions. The mineralogical sequence, melt composition and condensation temperature for all condensable elements were then quantified.

Our calculations show that the iron contents of olivine in equilibrium with a gas that is x100 enriched in CI-dust is consistent with that of amoeboid olivine aggregates and chondrules. Furthermore, our estimated temperature at which fayalite can form in these conditions is higher than what was previously proposed, enabling diffusion and homogenization of iron in olivine. The calculated composition of refractory metals for a x10 and x100 CI-dust enriched gas at 10⁻⁴ bar is consistent with the measured compositions of refractory metal nuggets. The possibility for these grains to have formed in an H₂O ice-enriched gas can be ruled out as the calculated fractionation patterns in this case did not match the observed compositions.

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多尘环境中主要元素和微量元素的凝结

最近的天文观测表明，尘埃可以局部集中在原行星盘上，形成环状结构。这些区域的热处理会导致尘埃蒸发和可冷凝元素中太阳能气体的局部富集。先前对主要元素行为的研究表明，这种富含尘埃的气体的冷凝可能导致硅酸盐熔体的形成，其成分类似于球粒。然而，以前的研究集中在富含灰尘的环境中，仅限于一组有限的元素。为了研究这些条件下凝析油的矿物学和化学成分，我们使用FactSage™软件对富含尘埃的太阳能气体进行了平衡计算。在10 - 6 bar和10 - 3 bar的压力范围内，ci -球粒陨石尘埃和h -球粒陨石尘埃的尘埃富集系数分别为1（太阳成分）、10和100。用新计算的活度系数精确地模拟了微量元素在不同固体溶液和熔体溶液中的凝结过程。可用的气相数据库中添加了新的微量元素，这些元素在氧化条件下是很重要的。定量测定了各可凝元素的矿物学序列、熔体组成和凝析温度。我们的计算表明，橄榄石的铁含量与一种富含100倍ci粉尘的气体平衡时的铁含量与变形虫橄榄石聚集体和球粒的铁含量一致。此外，我们估计的铁橄榄石在这些条件下形成的温度比之前提出的要高，这使得铁在橄榄石中的扩散和均匀化成为可能。在10 ~ 4 bar条件下，计算得到x10和x100含ci粉尘气体中难熔金属的组成与实测的难熔金属块的组成一致。这些颗粒在富含冰的水气体中形成的可能性可以排除，因为在这种情况下计算的分馏模式与观察到的成分不匹配。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Icarus 地学天文-天文与天体物理

CiteScore

6.30

自引率

18.80%

发文量

356

审稿时长

2-4 weeks

期刊介绍： Icarus is devoted to the publication of original contributions in the field of Solar System studies. Manuscripts reporting the results of new research - observational, experimental, or theoretical - concerning the astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of our Solar System or extrasolar systems are welcome. The journal generally does not publish papers devoted exclusively to the Sun, the Earth, celestial mechanics, meteoritics, or astrophysics. Icarus does not publish papers that provide "improved" versions of Bode''s law, or other numerical relations, without a sound physical basis. Icarus does not publish meeting announcements or general notices. Reviews, historical papers, and manuscripts describing spacecraft instrumentation may be considered, but only with prior approval of the editor. An entire issue of the journal is occasionally devoted to a single subject, usually arising from a conference on the same topic. The language of publication is English. American or British usage is accepted, but not a mixture of these.