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arXiv 2302.08657astro-ph.EP
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类谷神星小行星的晚期吸积及其注入外主带

Late Accretion of Ceres-like Asteroids and Their Implantation into the Outer Main Belt

Driss Takir, Wladimir Neumann, Sean N. Raymond, Joshua P. Emery, Mario Trieloff

摘要:

低丰度小行星保存了原始太阳系微行星的记录,以及太阳星云活跃的条件。然而,这些小行星的起源和演化并没有受到很好的约束。在这里,我们测量了可见光和近红外(0.5 - 4.0微米)光谱的低散射小行星在中部和外部的主带。我们发现,矮行星谷神星轨道外的许多大(d > 100 km)和暗(几何半径< 0.09)小行星与谷神星具有相同的光谱特征,并且可能是由相同的成分组成。我们还开发了一个热演化模型,表明这些谷神星状小行星具有高度多孔的内部,在富含钙铝的包裹体形成后的1.5 - 3.5百万年相对较晚地吸积,并且经历了< 900 K的最高内部温度。类似谷神星的小行星位于3.0 - 3.4天文单位之间的一个封闭的日心区域,但很可能是在这颗巨行星动力学不稳定期间从太阳系更遥远的区域注入的。

英文摘要:

Low-albedo asteroids preserve a record of the primordial solar system planetesimals and the conditions in which the solar nebula was active. However, the origin and evolution of these asteroids are not well-constrained. Here we measured visible and near-infrared (0.5 - 4.0 microns) spectra of low-albedo asteroids in the mid-outer main belt. We show that numerous large (d > 100 km) and dark (geometric albedo < 0.09) asteroids exterior to the dwarf planet Ceres' orbit share the same spectral features, and presumably compositions, as Ceres. We also developed a thermal evolution model that demonstrates that these Ceres-like asteroids have highly-porous interiors, accreted relatively late at 1.5 - 3.5 Myr after the formation of calcium-aluminum-rich inclusions, and experienced maximum interior temperatures of < 900 K. Ceres-like asteroids are localized in a confined heliocentric region between 3.0 - 3.4 au but were likely implanted from more distant regions of the solar system during the giant planet's dynamical instability.

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