The structure of protoplanetary discs around evolving young stars
The structure of protoplanetary discs around evolving young stars
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DOI：
10.1051/0004-6361/201424964
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发表时间：
2015-03-01
影响因子：
6.5
通讯作者：
Morbidelli, Alessandro
中科院分区：
文献类型：
--
作者：
Bitsch, Bertram;Johansen, Anders;Morbidelli, Alessandro
具有气态包层的行星的形成是在数百万年的时间尺度上发生在原行星吸积盘中的。微小的尘埃颗粒相互粘在一起形成鹅卵石，鹅卵石在湍流中浓缩形成小行星和行星胚胎，并成长为行星，行星经历了实质性的径向迁移。所有这些过程都受到原行星盘的基本结构的影响，特别是温度、气体标尺高度和密度的分布。最小质量太阳星云(MMSN)常用的盘状结构在所有这些量中都是一个简单的幂定律。然而，同时具有粘性和恒星加热的原行星盘模型显示，由于不透明度的转变，温度、标度高度和密度出现了几次颠簸和下降，这在MMSN模型中是缺失的。它们在行星的形成中扮演着重要的角色，因为它们可以作为通过流动不稳定性形成小行星的甜蜜点，并影响I型迁移的方向和大小。我们提供了以辐射冷却、粘性和恒星加热为特征的吸积盘的2D模拟，它们与观测到的原行星盘及其宿主恒星的演化阶段有关。这些模型使我们能够确定原行星盘中首选的小行星和行星形成区域，作为盘的金属丰度、吸积率和寿命的函数。我们推导出了几个MyR演化过程中原行星盘的所有结构特征的简单拟合公式。这些拟合直接适用于对行星的任何生长阶段进行建模，在这些阶段中，需要详细了解底层的圆盘结构。
The formation of planets with gaseous envelopes takes place in protoplanetary accretion discs on time scales of several million years. Small dust particles stick to each other to form pebbles, pebbles concentrate in the turbulent flow to form planetesimals and planetary embryos and grow to planets, which undergo substantial radial migration. All these processes are influenced by the underlying structure of the protoplanetary disc, specifically the profiles of temperature, gas scale height, and density. The commonly used disc structure of the minimum mass solar nebula (MMSN) is a simple power law in all these quantities. However, protoplanetary disc models with both viscous and stellar heating show several bumps and dips in temperature, scale height, and density caused by transitions in opacity, which are missing in the MMSN model. These play an important role in the formation of planets, since they can act as sweet spots for forming planetesimals via the streaming instability and affect the direction and magnitude of type-I migration. We present 2D simulations of accretion discs that feature radiative cooling and viscous and stellar heating, and they are linked to the observed evolutionary stages of protoplanetary discs and their host stars. These models allow us to identify preferred planetesimal and planet formation regions in the protoplanetary disc as a function of the disc's metallicity, accretion rate, and lifetime. We derive simple fitting formulae that feature all structural characteristics of protoplanetary discs during the evolution of several Myr. These fits are straightforward for applying to modelling any growth stage of planets where detailed knowledge of the underlying disc structure is required.