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

通过考虑来自中心T金牛座恒星的X射线和紫外线辐射，以及尘埃尺寸的增长和向盘中面的沉积，建立了原行星盘中气体和尘埃的密度和温度分布的详细模型。通过求解沉淀粉尘的凝聚方程，数值计算了粉尘粒子的空间分布和尺寸分布，结果表明，除中面外，圆盘内单位体积气体的粉尘粒子质量和总表面积都很小。利用得到的盘的物理结构计算了H_2能级布居和谱线发射。X射线辐射是内盘和表层气体的主要热源，而紫外光加热则占主导地位。当中心星具有强X射线和弱紫外辐射时，H_2能级布居受X射线泵浦的控制，可以观察到X射线诱导的跃迁谱线。如果紫外线辐射很强，能级粒子数就会受到热碰撞或紫外线泵浦的控制，具体取决于尘埃的性质。随着尘埃颗粒在磁盘中的演化，磁盘表面的气体温度下降，因为颗粒光电加热变得效率较低。这使得级别人口从LTE分布变为非LTE分布，从而导致线路比率发生变化。我们的结果表明，可以通过H_2谱线比观测到原行星盘中尘埃的演化。受强紫外线和X射线照射的圆盘发射线强，尘埃颗粒小，是观测H_2发射的好靶点。

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.