论文标题
一种分析解决方案，用于测量粘性自相似场景中原星盘中的气体大小
An analytic solution to measure the gas size in protoplanetary discs in the viscous self-similar scenario
论文作者
论文摘要
为了了解哪种机制负责原星盘中的积聚，使用$^{12} $ CO和其他CO的同位素同位素学等气体示踪剂对观察到的盘半径的强大知识是关键的。实际上，提出的两个主要理论是粘性积聚和风驱动的积聚，预测了圆盘半径的不同时间演变。在这封信中，我们提出了一种分析解决方案，用于使用$^{{12} $ CO作为示踪剂的粘性变化的原球盘的演变，假设$^{12} $ co radius是radius，而二家盘的表面密度等于Co photo-Photo-Phodo-Dissociation的表面密度。我们讨论了解决方案的特性及其适用性的限制，作为简单的数值处方，以评估椎间盘种群的观察到的光盘半径。我们的结果表明，除了散发照片外，还冻结在设置圆盘尺寸方面起着重要作用。我们发现，在CO散落位置的位置，CO丰度的有效降低了大约两个数量级，但是不应将其解释为圆盘中CO的大量丰度。我们的分析解决方案的使用将允许在不使用昂贵的计算资源（例如辐射转移计算）的情况下计算大量模型的圆盘尺寸。
In order to understand which mechanism is responsible for accretion in protoplanetary discs, a robust knowledge of the observed disc radius using gas tracers such as $^{12}$CO and other CO isotopologues is pivotal. Indeed, the two main theories proposed, viscous accretion and wind-driven accretion, predict different time evolution for the disc radii. In this Letter, we present an analytical solution for the evolution of the disc radii in viscously evolving protoplanetary discs using $^{12}$CO as a tracer, under the assumption that the $^{12}$CO radius is the radius where the surface density of the disc is equal to the threshold for CO photo-dissociation. We discuss the properties of the solution and the limits of its applicability as a simple numerical prescription to evaluate the observed disc radii of populations of discs. Our results suggest that, in addition to photo-dissociation, also freeze out plays an important role in setting the disc size. We find an effective reduction of the CO abundance by about two orders of magnitude at the location of CO photo-dissociation, which however should not be interpreted as the bulk abundance of CO in the disc. The use of our analytical solution will allow to compute disc sizes for large quantities of models without using expensive computational resources such as radiative transfer calculations.
