标题： 在过渡盘中培育超级地球和催生超级气态行星 显示英文标题

标题： Breeding Super-Earths and Birthing Super-Puffs in Transitional Disks

摘要： 超级地球（1-4$R_\oplus$，2-20$M_\oplus$）带来的谜题在于它们不是木星：它们的核心质量足够引发失控的气体吸积，但不知为何超级地球的 atmosphere 的重量只有其总质量的百分之几。 我们表明，如果超级地球形成得晚，在它们的母恒星气体盘即将消散时形成，这个谜团就可以解开。 这种情景似乎会带来精细调整的问题，但我们表明实际上没有这些问题。 环境中的气体密度可以跨越多个（多达9个）数量级，超级地球仍然可以在 $\sim$ 0.1-1 百万年后以按重量计百分之几的大气层形式稳健地出现。 超级地球核心自然是在气体贫乏的环境中孕育而成的，在这些环境中气体动力学摩擦已经减弱到足以让构成的原核心合并。 在核心组装时几乎没有气体存在，因此核心几乎不会因盘的扭矩而迁移：超级地球的形成可以是就地形成的。 这幅图景——即近距离的超级地球在内盘中形成，该内盘气体贫乏（但不是完全无气），通过从更外侧的更大盘中持续流入的气体提供燃料——让人联想到过渡盘中已经大范围清空但仍处于吸积状态的内部空腔。 我们还探讨了由超级气球（super-puffs）提出的问题：这是一种罕见的短周期行星类群，其体积似乎与其小质量不符（4-10$R_\oplus$，2-6$M_\oplus$）。 超级气球在外围 $\sim$ 1 AU以外作为无尘且快速冷却的世界，容易获得其厚大气层，那里星云气体更冷、密度更低、因此更透明。 与可以在本地形成的超级地球不同，超级气球向内迁移至当前轨道；它们预计会形成平均运动共振链的外部连接，并表现出更高的水分含量。 最后，我们将观察结果进行对比，并列出剩余的问题。 显示英文摘要

摘要： The riddle posed by super-Earths (1-4$R_\oplus$, 2-20$M_\oplus$) is that they are not Jupiters: their core masses are large enough to trigger runaway gas accretion, yet somehow super-Earths accreted atmospheres that weigh only a few percent of their total mass. We show that this puzzle is solved if super-Earths formed late, as the last vestiges of their parent gas disks were about to clear. This scenario would seem to present fine-tuning problems, but we show that there are none. Ambient gas densities can span many (up to 9) orders of magnitude, and super-Earths can still robustly emerge after $\sim$0.1-1 Myr with percent-by-weight atmospheres. Super-Earth cores are naturally bred in gas-poor environments where gas dynamical friction has weakened sufficiently to allow constituent protocores to merge. So little gas is present at the time of core assembly that cores hardly migrate by disk torques: formation of super-Earths can be in situ. The picture --- that close-in super-Earths form in a gas-poor (but not gas-empty) inner disk, fed continuously by gas that bleeds inward from a more massive outer disk --- recalls the largely evacuated but still accreting inner cavities of transitional protoplanetary disks. We also address the inverse problem presented by super-puffs: an uncommon class of short-period planets seemingly too voluminous for their small masses (4-10$R_\oplus$, 2-6$M_\oplus$). Super-puffs easily acquire their thick atmospheres as dust-free, rapidly cooling worlds outside $\sim$1 AU where nebular gas is colder, less dense, and therefore less opaque. Unlike super-Earths which can form in situ, super-puffs migrated in to their current orbits; they are expected to form the outer links of mean-motion resonant chains, and to exhibit greater water content. We close by confronting observations and itemizing remaining questions.