AI 中文总结
该研究以PDS 70 c与SR 12 c为观测对象，约束巨行星生长与卫星形成，发现其特性与木星-土星对相符，验证了相关卫星形成模型，为行星-卫星形成机制提供了观测支持。
AI 中文摘要
PDS 70 c和SR 12 c是仅有的拥有可靠冷亚毫米波盘探测结果的束缚行星质量天体，它们共同为巨行星生长和卫星形成提供了约束。PDS 70行星与我们太阳系中的木星-土星对存在显著相似性：两颗PDS 70行星均在一个共同的间隙内吸积，这关联了它们的最终质量、到达每个洛希球（Hill sphere）的物质以及环行星盘的特性。行星扭矩会耗尽这个有限的物质库，导致原行星打开恒星间隙时，环行星的物质供应随之减少。SR 12 c区分了行星生长与卫星形成的时间尺度：即便其当前质量生长时间尺度为(1.9±0.5)×10⁹年，气体和固体仍能留存。对于PDS 70 c，855微米流量在光学薄极限下意味着26 K温度下有0.007-0.031倍地球质量（M⊕）的尘埃；而在光学厚极限下，根据温度不同，共面半径的最小值为0.58-0.66天文单位（au），该尺度与通过已形成间隙的特定角动量（r_c~R_H/3）的后期气体流入相符。这些观测与我们针对木星和土星的卫星形成模型（Mosqueira & Estrada 2003a,b，2001年提交）一致，该模型中，卫星星子的气体拖曳清除使木卫四形成时间尺度约为10⁶年，土卫八约为10⁷年；PDS 70的年龄为5.4±1.0百万年（Myr），介于这两个数值之间。这些约束为平静、固体增强的卫星形成环境提供了有力支持，该环境在早期阶段与行星间隙演化耦合。
英文摘要
PDS~70~c and SR~12~c are the only bound planetary-mass objects with secure cold submillimeter disk detections. Together, these systems constrain giant-planet growth and satellite formation. The PDS~70 planets exhibit remarkable parallels to the Jupiter--Saturn pair in our Solar System. Both PDS~70 planets accrete within one shared gap, which links their final masses, the material reaching each Hill sphere, and the properties of the circumplanetary disk. Planetary torques deplete the finite interplanetary reservoir, causing circumplanetary supply to decline as the protoplanets open a circumstellar gap. SR~12~c separates the planetary-growth and satellite-formation timescales: gas and solids survive even though its current mass-growth timescale is $(1.9\pm0.6)\times10^9$~yr. For PDS~70~c, the 855-$μ$m flux implies $0.007$--$0.031\,\Mearth$ of dust at 26~K in the optically thin limit. A fully dust-dominated, uniform 22--26-K optically thick emitter has an equivalent coplanar radius of $0.58$--$0.66$~au, while a fiducial radial temperature profile yields an equivalent radius of approximately 0.46~au. The continuum constraints overlap the 0.5--1.5~au circularization range estimated by ballistic calculations of late-stage gap-fed inflow. We find that the PDS~70 constraints are consistent with our \SEMM{} satellite-formation model (Mosqueira \& Estrada 2003a,b, submitted in 2001). Thus the observations provide strong support for a quiescent, solids-enhanced satellite-forming environment, coupled in the early stages to planetary-gap evolution.
