An Ideal Testbed for Planet–Disk Interaction: Two Giant Protoplanets in Resonance Shaping the PDS 70 Protoplanetary Disk
An Ideal Testbed for Planet–Disk Interaction: Two Giant Protoplanets in Resonance Shaping the PDS 70 Protoplanetary Disk
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DOI：
10.3847/2041-8213/ab46b0
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发表时间：
2019-09
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通讯作者：
J. Bae;Zhaohuan Zhu;C. Baruteau;M. Benisty;C. Dullemond;S. Facchini;A. Isella;M. Keppler;L. P'ere
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作者：
J. Bae;Zhaohuan Zhu;C. Baruteau;M. Benisty;C. Dullemond;S. Facchini;A. Isella;M. Keppler;L. P'ere
虽然数值模拟在行星盘相互作用的研究中发挥着关键作用，但迄今为止根据观测结果测试数值结果仍然有限。 PDS 70 的星周盘中嵌入了两颗直接成像的原行星，为行星盘相互作用研究提供了理想的测试平台。使用二维流体动力学模拟，我们表明观察到的特征可以很好地解释两颗正在形成的行星，这提供了强有力的证据，证明先前提出的行星盘相互作用理论正在发挥作用，包括共振迁移、粒子捕获、尺寸分离和过滤。我们的模拟表明，这两颗行星可能处于 2:1 的平均运动共振状态，并且可以在数百万年的时间尺度上保持动态稳定。行星以 10−8–10−7 MJup yr−1 的速度增长，其速率与 Hα 观测的估计相当，不会破坏共振结构的稳定。大颗粒在间隙边缘被过滤，只有小的（亚）μm 颗粒可以流向环行星盘（CPD）和内部星周盘。通过在两颗直接成像的行星外部观察到亚毫米连续环，PDS 70 提供了第一个关于间隙打开的行星过滤粒子的观测证据。当（亚）微米颗粒在多个 CPD 气体粘性时间尺度上存活并在其中积累时，可以重现在行星附近观察到的亚毫米连续发射。其中一种可能性是，（亚）微米颗粒的尺寸是否会增大并仍然被困在压力凸起中，类似于我们在星周盘中发现的情况。我们讨论对太阳系中行星形成和成熟的太阳系外行星系统的潜在影响。
While numerical simulations have been playing a key role in the studies of planet–disk interaction, testing numerical results against observations has been limited so far. With the two directly imaged protoplanets embedded in its circumstellar disk, PDS 70 offers an ideal testbed for planet–disk interaction studies. Using two-dimensional hydrodynamic simulations we show that the observed features can be well explained with the two planets in formation, providing strong evidence that previously proposed theories of planet–disk interaction are in action, including resonant migration, particle trapping, size segregation, and filtration. Our simulations suggest that the two planets are likely in 2:1 mean motion resonance and can remain dynamically stable over million-year timescales. The growth of the planets at 10−8–10−7 MJup yr−1, rates comparable to the estimates from Hα observations, does not destabilize the resonant configuration. Large grains are filtered at the gap edge and only small, (sub-)μm grains can flow to the circumplanetary disks (CPDs) and the inner circumstellar disk. With the submillimeter continuum ring observed outward of the two directly imaged planets, PDS 70 provides the first observational evidence of particle filtration by gap-opening planets. The observed submillimeter continuum emission at the vicinity of the planets can be reproduced when (sub-)μm grains survive over multiple CPD gas viscous timescales and accumulate therein. One such possibility is if (sub-)μm grains grow in size and remain trapped in pressure bumps, similar to what we find happening in circumstellar disks. We discuss potential implications to planet formation in the solar system and mature extrasolar planetary systems.