论文标题
Protoplanet的气体包膜中鹅卵石的运输，破坏和生长
Transport, destruction and growth of pebbles in the gas envelope of a protoplanet
论文作者
论文摘要
我们分析了由相对沉积速度以及对流气体运动驱动的碰撞，分析了在原行星盘中生长的原球星的气态包膜的大小演变。使用基于卵石积聚发光度的对流气速的简单估计，我们发现对流气体的速度高于小于1 mm的所有颗粒的沉积速度。这意味着卵石和卵石碎片都受对流气体运动的强烈影响，并且将由大规模对流电池运输，均向原始球星的表面和远离protoplanet的表面运输。我们提出了一个简单的方案，以考虑侵蚀，传质和碎片的影响，以发展卵石的特征大小。包括对流细胞的向下运动，用于以1毫米的初始半径运输鹅卵石，我们发现卵石大小在100微米和1毫米的卵石尺寸附近。这些尺寸通常可以在对流流的底部积聚。远离恒星（> 30 au）的小原子星形却将卵石侵蚀至10微米以下的尺寸；将需要未来的流体动力学模拟来确定如此小的碎片是否可以从对流流中脱离并被原plynatet积聚。
We analyse the size evolution of pebbles accreted into the gaseous envelope of a protoplanet growing in a protoplanetary disc, taking into account collisions driven by the relative sedimentation speed as well as the convective gas motion. Using a simple estimate of the convective gas speed based on the pebble accretion luminosity, we find that the speed of the convective gas is higher than the sedimentation speed for all particles smaller than 1 mm. This implies that both pebbles and pebble fragments are strongly affected by the convective gas motion and will be transported by large-scale convection cells both towards and away from the protoplanet's surface. We present a simple scheme for evolving the characteristic size of the pebbles, taking into account the effects of erosion, mass transfer and fragmentation. Including the downwards motion of convective cells for the transport of pebbles with an initial radius of 1 millimeter, we find pebble sizes between 100 microns and 1 millimeter near the surface of the protoplanet. These sizes are generally amenable to accretion at the base of the convection flow. Small protoplanets far from the star (>30 AU) nevertheless erode their pebbles to sizes below 10 microns; future hydrodynamical simulations will be needed to determine whether such small fragments can detach from the convection flow and become accreted by the protoplanet.
