Water in protoplanetary disks : deuteration and turbulent mixing
Water in protoplanetary disks : deuteration and turbulent mixing
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原行星盘中的水：氘化和湍流混合
DOI：
10.1088/0004-637x/779/1/11
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
V.
中科院分区：
文献类型：
--
作者：
Furuya;K.;Aikawa;Y.;Nomura;H.;Hersant. F.;Wakelam;V.
我们研究水和氘水化学在湍流原行星盘。化学速率方程求解的扩散项，模仿湍流混合在垂直方向。中平面附近的水通过湍流被输送到盘大气，并通过光反应被破坏以产生原子氧，而原子氧被输送到中平面并重新形成水和/或其他分子。我们发现，这个周期显着降低柱密度的水冰在r = 30 Au，尘埃温度太高，有效地改革水冰。该区域的径向范围取决于氢原子的脱附能。我们的模型表明，即使在升华半径之外，水冰也可能不足。在这个半径之外，循环会在10 - 6年内将水冰的氘氢比（D/H）从坍缩核心模型设定的10 - 2× 10 - 2降低到10 - 4-10 - 2，而不会显著降低水冰柱的密度。所得的D/H比取决于混合强度和距中心星星的径向距离。我们的发现表明，彗星水的D/H比（1010 − 4）可以在太阳星云中建立（即彗星水可以形成），即使输送到圆盘的水冰的D/H比非常高（1010 − 2）。
We investigate water and deuterated water chemistry in turbulent protoplanetary disks. Chemical rate equations are solved with the diffusion term, mimicking turbulent mixing in a vertical direction. Water near the midplane is transported to the disk atmosphere by turbulence and is destroyed by photoreactions to produce atomic oxygen, while the atomic oxygen is transported to the midplane and reforms water and/or other molecules. We find that this cycle significantly decreases column densities of water ice at r≲ 30 AU, where dust temperatures are too high to reform water ice effectively. The radial extent of such region depends on the desorption energy of atomic hydrogen. Our model indicates that water ice could be deficient even outside the sublimation radius. Outside this radius, the cycle decreases the deuterium-to-hydrogen (D/H) ratio of water ice from∼ 2× 10− 2, which is set by the collapsing core model, to 10− 4–10− 2 in 10 6 yr, without significantly decreasing the water ice column density. The resultant D/H ratios depend on the strength of mixing and the radial distance from the central star. Our finding suggests that the D/H ratio of cometary water (∼ 10− 4) could be established (ie, cometary water could be formed) in the solar nebula, even if the D/H ratio of water ice delivered to the disk was very high (∼ 10− 2).