Collisional Cascades in Planetesimal Disks. II. Embedded Planets
Collisional Cascades in Planetesimal Disks. II. Embedded Planets
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星子盘中的级联碰撞。
DOI：
10.1086/379854
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
B. Bromley
中科院分区：
文献类型：
--
作者：
S. Kenyon;B. Bromley
我们使用一个多环的星子吸积代码来研究在星子盘的外部区域的冰行星的生长。在一个静止的最小质量太阳星云中，冰冷的行星在tP <$（15-20）[a/（30 Au）]3百万年的时间尺度上增长到1000-3000公里的大小，其中a是到中心星星的距离。行星在更大质量的星云中形成得更快。新形成的行星沿着它们的轨道搅动沿着剩余的微行星，并产生一个碰撞级联，在这个级联中，冰冷的微行星慢慢地被磨成尘埃。行星形成时的尘埃碎片具有类似于β Pic和HR 4796 A以及其他碎片盘中观测到的物理特征。计算的尘埃质量为Md（r = 1 mm）<$1026（M0/MMMSN）g和Md（1 mm <$r = 1 m）<$1027（M0/MMMSN）g，其中r是粒子的半径，M0是初始固体质量，MMMSN是30-150 Au的最小质量太阳星云的固体质量。尘埃盘的光度与恒星光度的关系是LD/L0 <$Lmax（t/t0）-m，其中Lmax <$10 -3（M0/MMMSN），t0 <$10 -1000 Myr，m <$1 -2。我们的计算产生了亮环和暗隙，大小为Δa/a ≤ 0.1。明亮的光环出现在最近形成的1000公里或更大的行星上。暗隙是行星清除尘埃的区域，或者是行星尚未形成的阴影。行星也可以在受到星星近距离通过扰动的星子盘中生长。恒星飞掠引发碰撞级联，产生大量的尘埃。在一个小扰动之后，尘埃的光度比静止的行星形成盘的最大尘埃光度大3-4倍。在1000万年或更短的时间内，大的扰动几乎将所有的星子从盘中移走。经过适度的飞越后，碰撞阻尼降低了微行星的速度，并允许行星从剩余的微行星中生长。行星形成的时间尺度比未受干扰的圆盘的时间尺度长2-4倍;尘埃光度小2-4倍。
We use a multiannulus planetesimal accretion code to investigate the growth of icy planets in the outer regions of a planetesimal disk. In a quiescent minimum-mass solar nebula, icy planets grow to sizes of 1000–3000 km on a timescale tP ≈ (15–20)[a/(30 AU)]3 Myr, where a is the distance from the central star. Planets form faster in more massive nebulae. Newly formed planets stir up leftover planetesimals along their orbits and produce a collisional cascade in which icy planetesimals are slowly ground to dust. The dusty debris of planet formation has physical characteristics similar to those observed in β Pic and HR 4796A and other debris disks. The computed dust masses are Md(r ≲ 1 mm) ∼ 1026(M0/MMMSN) g and Md(1 mm ≲ r ≲ 1 m) ∼ 1027(M0/MMMSN) g, where r is the radius of a particle, M0 is the initial mass in solids, and MMMSN is the mass in solids of a minimum-mass solar nebula at 30–150 AU. The luminosity of the dusty disk relative to the stellar luminosity is LD/L0 ∼ Lmax(t/t0)-m, where Lmax ∼ 10-3(M0/MMMSN), t0 ≈ 10–1000 Myr, and m ≈ 1–2. Our calculations produce bright rings and dark gaps with sizes Δa/a ≈ 0.1. Bright rings occur where planets 1000 km and larger have recently formed. Dark gaps are regions where planets have cleared out dust, or shadows where planets have yet to form. Planets can also grow in a planetesimal disk perturbed by the close passage of a star. Stellar flybys initiate collisional cascades, which produce copious amounts of dust. The dust luminosity following a modest perturbation is 3–4 times larger than the maximum dust luminosity of a quiescent planet-forming disk. In 10 Myr or less, large perturbations remove almost all of the planetesimals from a disk. After a modest flyby, collisional damping reduces planetesimal velocities and allows planets to grow from the remaining planetesimals. Planet formation timescales are then 2–4 times longer than timescales for undisturbed disks; dust luminosities are 2–4 times smaller.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell