From Solar System Formation Theory "Kyoto Model" to General Theory of Planetary Systems "Kobe Model"

通过考虑来自金牛座T星中心的x射线和紫外线辐射，以及尘埃大小的增长和向圆盘中部沉降，构建了原行星盘中气体和尘埃密度和温度分布的详细模型。通过求解沉降尘粒的凝聚方程，数值计算了尘粒的空间分布和尺寸分布，结果表明，除中间面外，圆盘内气体单位体积内尘粒的质量和总表面积都很小。利用导出的磁盘物理结构计算了H_2能级居群和线发射。x射线辐射是内盘和表层气体的主要热源，而紫外线加热则占主导地位。如果中心星具有强x射线和弱紫外辐射，则H_2能级居群受x射线抽运控制，可以观测到x射线诱导的过渡线。如果紫外线照射很强，则根据粉尘的性质，通过热碰撞或紫外线泵送来控制水平种群。随着尘埃颗粒在盘内的演化，由于颗粒光电加热效率降低，盘表面气体温度下降。这使得电平人口从LTE到非LTE分布发生变化，从而导致线路比率的变化。我们的结果表明，可以通过H_2线比值来观测原行星盘中的尘埃演化。由于受到强紫外线和x射线的照射，并含有小尘埃颗粒，因此发射线很强；这样的圆盘将是观测H_2发射的良好目标。

Detailed models for the density and temperature profiles of gas and dust in protoplanetary disks are constructed by taking into account X-ray and UV irradiation from a central T Tauri star, as well as dust size growth and settling toward the disk midplane. The spatial and size distributions of dust grains are numerically computed by solving the coagulation equation for settling dust particles, with the result that the mass and total surface area of dust grains per unit volume of the gas in the disks are very small, except at the midplane. The H_2 level populations and line emission are calculated using the derived physical structure of the disks. X-ray irradiation is the dominant heating source of the gas in the inner disk and in the surface layer, while the UV heating dominates otherwise. If the central star has strong X-ray and weak UV radiation, the H_2 level populations are controlled by X-ray pumping, and the X-ray-induced transition lines could be observable. If the UV irradiation is strong, the level populations are controlled by thermal collisions or UV pumping, depending on the dust properties. As the dust particles evolve in the disks, the gas temperature at the disk surface drops because the grain photoelectric heating becomes less efficient. This makes the level populations change from LTE to non-LTE distributions, which results in changes to the line ratios. Our results suggest that dust evolution in protoplanetary disks could be observable through the H_2 line ratios. The emission lines are strong from disks irradiated by strong UV and X-rays and possessing small dust grains ; such disks will be good targets in which to observe H_2 emission.