Metallicity dependence of dust growth in a protoplanetary disk
arxiv(2024)
摘要
In the context of planet formation, growth from micron-sized grains to
kilometer-sized planetesimals is a crucial question. Since the dust growth rate
depends on the amount of dust, realizing planet formation scenarios based on
dust growth is challenging in environments with low metallicity, i.e. less
dust. We investigate dust growth during disk evolution, particularly focusing
on the relationship with metallicity. We perform two-dimensional thin-disk
hydrodynamic simulations to track the disk evolution over 300 kyr from its
formation. The dust motion is solved separately from the gas motion, with its
distribution changing due to drag forces from the gas. Dust size growth is also
accounted for, with the magnitude of the drag force varying according to the
dust size. We employ three models with metallicities of 1.0, 0.1, and 0.01
Z_⊙, i.e. dust-to-gas mass ratios of 10^-2, 10^-3, and
10^-4, respectively. In the disks with the metallicities ≥0.1 Z_⊙, the dust radii reach cm sizes, consistent with estimations from
the dust growth timescale. Conversely, for the metallicity of 0.01 Z_⊙, the maximum dust size is only 10^-2 cm, with almost no growth
observed across the entire disk scale (∼100 au). At the metallicities
≥0.1 Z_⊙, the decoupling between grown dust and gas leads to
non-uniform dust-to-gas mass ratios. However, deviations from the canonical
value of this ratio have no impact on the gravitational instability of the
disk. The formation of dust rings is confirmed in the innermost part of the
disk (∼10–30 au). The dust rings where the dust-to-gas mass ratio is
enhanced, and the Stokes number reaches ∼0.1, are suitable environments
for the streaming instability. We conjecture that planetesimal formation occurs
through the streaming instability in these dust rings.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要