THE IMPACT OF DUST EVOLUTION AND PHOTOEVAPORATION ON DISK DISPERSAL
THE IMPACT OF DUST EVOLUTION AND PHOTOEVAPORATION ON DISK DISPERSAL
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DOI：
10.1088/0004-637x/804/1/29
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发表时间：
2015-02
期刊：
影响因子：
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通讯作者：
U. Gorti;D. Hollenbach;C. Dullemond
中科院分区：
文献类型：
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作者：
U. Gorti;D. Hollenbach;C. Dullemond
原行星盘在几百万年里通过黏性演化和光蒸发而分散；在此期间，亚微米大小的尘埃颗粒必须生长并形成行星。随时间变化的小颗粒丰度直接影响远紫外（FUV）光子对气体的加热，而尘埃的演变通过改变盘的不透明度和导致远紫外光子在盘中的渗透来影响光蒸发。光蒸发流，反过来，选择性地携带小尘埃颗粒，留下较大的颗粒-与气体分离-在圆盘后面。为了研究这些影响，我们使用一维多流体方法（气体+不同尘埃颗粒大小）来求解表面密度分布的演变，研究了圆盘受粘度、EUV、FUV和x射线光蒸发、尘埃演变和径向漂移影响的演变。通过在每个历元构建1+1D模型来增强一维演化，以获得瞬时圆盘结构并确定光蒸发速率。与没有粉尘演化的模型相比，粉尘凝聚/碎片模型的实现导致磁盘寿命的边际减少；因此，我们发现圆盘的寿命对不断变化的尘埃不透明度相对不敏感。我们发现，光蒸发可以导致盘内行星形成区域的气体/尘埃质量比显著降低，并可能导致相对于氢的重元素丰度相应增加。我们讨论了对小行星形成和巨行星形成理论的启示，包括贫气巨行星的形成。气体盘扩散后，~ 3 × 10−4 ？bbbbm⊙？通常会保留100亿美元的固体质量，与我们太阳系的固体库存相当。
Protoplanetary disks are dispersed by viscous evolution and photoevaporation in a few million years; in the interim small, sub-micron-sized dust grains must grow and form planets. The time-varying abundance of small grains in an evolving disk directly affects gas heating by far-ultraviolet (FUV) photons, while dust evolution affects photoevaporation by changing the disk opacity and resulting penetration of FUV photons in the disk. Photoevaporative flows, in turn, selectively carry small dust grains, leaving the larger particles—which decouple, from the gas—behind in the disk. We study these effects by investigating the evolution of a disk subject to viscosity, photoevaporation by EUV, FUV, and X-rays, dust evolution, and radial drift using a one-dimensional (1D) multi-fluid approach (gas + different dust grain sizes) to solve for the evolving surface density distributions. The 1D evolution is augmented by 1+1D models constructed at each epoch to obtain the instantaneous disk structure and determine photoevaporation rates. The implementation of a dust coagulation/fragmentation model results in a marginal decrease in disk lifetimes when compared to models with no dust evolution; the disk lifetime is thus found to be relatively insensitive to the evolving dust opacity. We find that photoevaporation can cause significant reductions in the gas/dust mass ratio in the planet-forming regions of the disk as it evolves, and may result in a corresponding increase in heavy element abundances relative to hydrogen. We discuss implications for theories of planetesimal formation and giant planet formation, including the formation of gas-poor giants. After gas disk dispersal, ∼ 3 × 10 − 4 ?> M ⊙ ?> of mass in solids typically remain, comparable to the solids inventory of our solar system.