The Planetary Accretion Shock. II. Grid of Postshock Entropies and Radiative Shock Efficiencies for Nonequilibrium Radiation Transport
The Planetary Accretion Shock. II. Grid of Postshock Entropies and Radiative Shock Efficiencies for Nonequilibrium Radiation Transport
复制标题
行星吸积冲击。
DOI：
10.3847/1538-4357/ab245b
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
R. Kuiper
中科院分区：
文献类型：
--
作者：
G. Marleau;C. Mordasini;R. Kuiper
在气体巨星的核心吸积形成场景中，大多数气体吸积到行星上是通过吸积激波处理的。在这一系列的论文中，我们研究这一冲击，因为它是确定形成中的行星结构的关键，因此它的形成后光度具有戏剧性的观测结果。我们进行一维灰色辐射流体动力学模拟与非平衡（两个温度）辐射输运和最新的不透明度。我们调查的吸积率，行星质量，行星半径的参数空间，并获得激波后的温度，压力，熵，以及全球辐射效率。我们发现，冲击温度通常是由“自由流动”的限制。在低温下，尘埃的不透明度会使激波变热，但并不显著。我们证实了这一点与原来的半解析推导。我们还估计了激波和星云之间的光度变化。无论是光度分布还是光度分布都不直接依赖于激波和星云之间的光学深度。相反，取决于即时震前不透明度和状态方程上的光度变化。我们发现相当高的冲击后立即熵（-20），这使得冲击似乎不太可能冷却地球。全球辐射效率很高（），但进入行星的总能量的剩余部分超过经典冷启动的内部光度几个数量级。总的来说，这些发现表明热启动或热启动更合理。
In the core-accretion formation scenario of gas giants, most of the gas accreting onto a planet is processed through an accretion shock. In this series of papers we study this shock because it is key in setting the structure of the forming planet and thus its postformation luminosity, with dramatic observational consequences. We perform one-dimensional gray radiation-hydrodynamical simulations with nonequilibrium (two-temperature) radiation transport and up-to-date opacities. We survey the parameter space of accretion rate, planet mass, and planet radius and obtain postshock temperatures, pressures, and entropies, as well as global radiation efficiencies. We find that the shock temperature is usually given by the “free-streaming” limit. At low temperatures the dust opacity can make the shock hotter but not significantly so. We corroborate this with an original semianalytical derivation of . We also estimate the change in luminosity between the shock and the nebula. Neither nor the luminosity profile depend directly on the optical depth between the shock and the nebula. Rather, depends on the immediate preshock opacity, and the luminosity change on the equation of state. We find quite high immediate postshock entropies ( –20 ), which makes it seem unlikely that the shock can cool the planet. The global radiation efficiencies are high ( ), but the remainder of the total incoming energy, which is brought into the planet, exceeds the internal luminosity of classical cold starts by orders of magnitude. Overall, these findings suggest that warm or hot starts are more plausible.
DOI：
10.1088/0004-637x/807/1/2
发表时间：
2015-05
期刊：
The Astrophysical Journal
影响因子：
--
作者：
L. Cleeves;E. Bergin;T. J. H. U. O. Michigan;U. Exeter
通讯作者：
L. Cleeves;E. Bergin;T. J. H. U. O. Michigan;U. Exeter
影响因子：
4.9
作者：
Baraffe, I.;Vorobyov, E.;Chabrier, G.
通讯作者：
Chabrier, G.