岩质行星的挥发性元素亏损：混合吸积的化学指纹
Volatile depletion in rocky planets as a chemical fingerprint of hybrid accretion
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中文总结 AI 辅助
本研究结合 pebble 吸积与星子碰撞生长建模，发现挥发性元素亏损是类地行星混合吸积的化学指纹，可通过元素特征推断行星吸积历史，为解释岩质系外行星化学多样性提供依据。
中文摘要 AI 辅助
岩质行星相对于其宿主恒星的挥发性元素亏损在太阳系和系外行星系统中都十分常见，但行星形成与成分之间的关联仍不明确。本研究结合 pebble 吸积过程中的去挥发作用与挥发性元素亏损星子的碰撞生长，对地球和火星的形成路径进行建模。通过贝叶斯推断，研究发现，硅酸盐地球（Bulk Silicate Earth）的最佳拟合模型来自两个通过 pebble 吸积形成的原行星贡献至少75%的物质，辅以最多约25%的、成分类似灶神星（Vesta）的星子物质；若采用未在已知陨石母体中观测到的星子挥发性亏损曲线，则星子贡献可达到40%（误差范围为+15%至-14%）。相比之下，硅酸盐火星反映了27±5%的 pebble 吸积物质和73±5%的灶神星类星子物质。研究确定，挥发性元素亏损是混合吸积的化学指纹，其中 pebble 吸积与碰撞聚集共同类类地行星的生长。通过将形成路径与挥发性预算定量关联，研究结果表明可通过元素特征推断行星吸积历史，对解释岩质系外行星的化学多样性具有广泛意义。
英文摘要
Volatile depletion in rocky planets relative to their host stars is commonplace in both the Solar System and exoplanetary systems, yet the connections between planet formation and composition remain elusive. Here we model devolatilization during pebble accretion in combination with collisional growth from volatile-depleted planetesimals to explore the formation pathways of Earth and Mars. Using Bayesian inference, we find that bulk silicate Earth is best reproduced by ${\gtrsim}$75% contribution from two protoplanets formed via pebble accretion, supplemented by up to $\sim$25% material from planetesimals that are compositionally akin to the asteroid Vesta. Using instead a planetesimal volatile-depletion curve that is not observed among known meteorite parent bodies would allow the planetesimal contribution to reach 40$^{+15}_{-14}$%. In comparison, bulk silicate Mars reflects 27$\pm$5% pebble-accreted material and 73${\pm}$5% Vesta-like planetesimals. We identify volatile depletion as a chemical fingerprint of hybrid accretion, in which both pebble accretion and collisional assembly contribute to terrestrial planet growth. By quantitatively linking formation pathways to volatile budgets, our findings demonstrate how planetary accretion histories can be inferred from elemental signatures, with broad implications for interpreting the chemical diversity of rocky exoplanets.
发表机构
- University of Copenhagen（哥本哈根大学）
- ETH Zürich（苏黎世联邦理工学院）
- University of Alabama（阿拉巴马大学）
- University of Nevada, Las Vegas（内华达大学拉斯维加斯分校）
- University of Arizona（亚利桑那大学）
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