arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2011.00022astro-ph.EP
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偏心轨道行星的三维绕流场

The Three Dimensional Flow Field Around Planets on Eccentric Orbits

Avery Bailey, Jim Stone, Jeffrey Fung

摘要:

我们调查的偏心原行星周围的流体动力学流动的性质,并比较它们与经常假设的圆形轨道的情况下。为此,我们进行了一组3D流体动力学模拟的原行星与小偏心率($e\leq 0.1$)。我们采用等温状态方程和集中分辨率的原行星调查流量下降到原行星的环行星盘(CPD)的规模。我们发现增强的外CPD低行星质量进行亚音速偏心运动的旋转。如果偏心率大到足以形成弓形激波,这种趋势就会逆转,自转变得越来越逆行。瞬时偏心流场显着改变相比,圆形轨道。而后者表现出的极性流入和中平面流出的通用模式,在偏心的情况下,流的几何形状取决于轨道相位。即使是在这里测试的适度偏心率,流入的主要来源可以来自中平面而不是极点。我们发现,流入和流出的量增加较高的$e$和较低的原行星质量,从而通过行星的邦迪半径回收更多的气体。这些增加的流量可能会增加卵石吸积率偏心行星的几倍,圆轨道率。作为对偏心运动的响应,行星的CPD的结构和旋转保持不变。由于CPD调节气体最终吸积到行星上,我们预测偏心和圆形行星之间的气体吸积率变化不大。

英文摘要:

We investigate the properties of the hydrodynamic flow around eccentric protoplanets and compare them with the often assumed case of a circular orbit. To this end, we perform a set of 3D hydrodynamic simulations of protoplanets with small eccentricities ($e\leq 0.1$). We adopt an isothermal equation of state and concentrate resolution on the protoplanet to investigate flows down to the scale of the protoplanet's circumplanetary disk (CPD). We find enhanced prograde rotation exterior to the CPD for low planet masses undergoing subsonic eccentric motion. If the eccentricity is made large enough to develop a bow shock, this trend reverses and rotation becomes increasingly retrograde. The instantaneous eccentric flow field is dramatically altered compared to circular orbits. Whereas the latter exhibit a generic pattern of polar inflow and midplane outflow, the flow geometry depends on orbital phase in the eccentric case. For even the modest eccentricities tested here, the dominant source of inflow can come from the midplane instead of the poles. We find that the amount of inflow and outflow increases for higher $e$ and lower protoplanet masses, thereby recycling more gas through the planet's Bondi radius. These increased fluxes may increase the pebble accretion rate for eccentric planets up to several times that of the circular orbit rate. In response to eccentric motion, the structure and rotation of the planet's bound CPD remains unchanged. Because the CPD regulates the eventual accretion of gas onto the planet, we predict little change to the gas accretion rates between eccentric and circular planets.

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