We investigate whether the regular Galilean satellites could have formed in the dead zone of a circumplanetary disc. A dead zone is a region of weak turbulence in which the magnetorotational instability (MRI) is suppressed, potentially an ideal environment for satellite formation. With the grid-based hydrodynamic code, FARGO3D, we examine the evolution of a circumplanetary disc model with a dead zone. Material accumulates in the dead zone of the disc leading to a higher total mass and but a similar temperature profile compared to a fully turbulent disc model. The tidal torque increases the rate of mass transport through the dead zone leading to a steady state disc with a dead zone that does not undergo accretion outbursts. We explore a range of disc, dead zone and mass inflow parameters and find that the maximum mass of the disc is around 0.001 MJ . Since the total solid mass of such a disc is much lower, we find that there is not sufficient material in the disc for in situ formation of the Galilean satellites and that external supplement is required.
Circumplanetary discs can be linearly unstable to the growth of disc tilt in the tidal potential of the star-planet system. We use three-dimensional hydrodynamical simulations to characterize the disc conditions needed for instability, together with its long term evolution. Tilt growth occurs for disc aspect ratios, evaluated near the disc outer edge, of $H/r\gtrsim 0.05$, with a weak dependence on viscosity in the wave-like regime of warp propagation. Lower mass giant planets are more likely to have circumplanetary discs that satisfy the conditions for instability. We show that the tilt insta…
We investigated the formation and evolution of satellite systems in a cold, extended circumplanetary disc around a 10 $M_{\rm{Jupiter}}$ gas giant which was formed by gravitational instability at 50\,AU from its star. The disc parameters were from a 3D global SPH simulation. We used a population synthesis approach, where we placed satellite embryos in this disc, and let them accrete mass, migrate, collide until the gaseous disc is dissipated. In each run we changed the initial dust-to-gas ratio, dispersion- and refilling time-scales within reasonable limits, as well as the number of embryos an…
It has been considered that large satellites around gas planets form in-situ circumplanetary discs (CPDs). However, dust particles supplied into CPDs drift toward the central planets before they grow into satellitesimals, building blocks of the satellites. We investigate the dust growth in laminar CPDs with magnetic wind-driven accretion. In such laminar discs, dust particles can settle onto the mid-plane and grow large by mutual collision more efficient than in classical turbulent CPDs. First, we carry out 3D local MHD simulations of a CPD including all the nonideal MHD effects (Ohmic resisti…
Circumplanetary discs (CPDs) form around young gas giants and are thought to be the sites of moon formation as well as an intermediate reservoir of gas that feeds the growth of the gas giant. How the physical properties of such CPDs are affected by the planetary mass and the overall opacity is relatively poorly understood. In order to clarify this, we use the global radiation hydrodynamics code FARGOCA, with a grid structure that allows resolving the planetary gravitational potential sufficiently well for a CPD to form. We then study the gas flows and density/temperature structures that emerge…
The satellites of Jupiter are thought to form in a circumplanetary disc. Here we address their formation and orbital evolution with a population synthesis approach, by varying the dust-to-gas ratio, the disc dispersal timescale and the dust refilling timescale. The circumplanetary disc initial conditions (density and temperature) are directly drawn from the results of 3D radiative hydrodynamical simulations. The disc evolution is taken into account within the population synthesis. The satellitesimals were assumed to grow via streaming instability. We find that the moons form fast, often within…
Shock-driven Accretion in Circumplanetary Disks: Observables and Satellite Formation
环行星盘（CPD）控制行星的生长，为卫星的形成提供材料，并提供年轻行星形成的观测特征。我们进行了二维流体动力学模拟和辐射冷却的研究CPD，并提出了一个新的机制来驱动盘吸积。CPD中存在两个螺旋激波，由中央恒星激发。我们发现，螺旋激波可以至少有助于，如果不是占主导地位的角动量输运和能量耗散在CPD。同时，螺旋激波的耗散和加热对激波驱动的吸积本身有正反馈作用。当盘被螺旋冲击加热时，冲击变得更加开放，导致更有效的角动量传输。另一方面，这种激波驱动的吸积在几个月/几年的时间尺度上是不稳定的，这是由于盘中涡旋的产生和破坏。在经过一段时间的平均后，从行星的希尔半径一直到行星表面都达到了准稳定的吸积，而表征螺旋激波引起的角动量传输的圆盘系数$α$为$\sim$ 0.001-0.02。在我们的模拟中，盘表面密度范围从10到1000 g cm $^{-2}$，这比用于研究卫星形成的“最小质量亚星云”模型小至少3个数量级;相反，它与“气体匮乏”卫星形成模型更一致。最后，我们计算的毫米波流量发射的CPD在ALMA和EVLA波段，并预测最近发现的CPD候选人，这表明ALMA是能够发现这些吸积CPD的通量。
An upper limit on the mass of the circumplanetary disk for DH Tau b
DH Tau是一颗年轻的（$\sim$ 100万年）经典金牛座T星。它是少数已知与行星质量伴星DH Tau b相关的年轻PMS星之一，其轨道距离很大，并通过直接成像检测到。DH Tau b被认为是基于大量的H $α$发射而吸积的，并且表现出可变的Paschen Beta发射。在230 GHz的NOEMA观测允许我们把限制盘尘埃质量的DH头b和主要的制度，磁盘将出现光学薄。我们估计一个磁盘尘埃质量的主要，DH头A的$17.2\pm1.7\,M_{\oplus}$，这给出了一个磁盘到恒星的质量比为0.014（假设通常的气体和尘埃的质量比为100的磁盘）。我们发现一个保守的磁盘尘埃质量上限为0.42 $M_{\oplus}$ DH头b，假设磁盘温度主要是由DH头b本身的辐射。考虑到环行星盘的环境，来自周围云的原始或平衡温度的可变照明将导致更低的盘质量估计。包括DH Tau b和DH Tau A对环行星盘加热的MCFOST辐射转移模型表明，22 K的质量平均盘温度更现实，导致DH Tau b的尘埃盘质量上限为0.09 $M_{\oplus}$。我们将DH Tau b置于类似物体的背景下，并讨论了行星形成模型的后果。
Recent imaging of the disc around the V4046$\,$Sgr spectroscopic binary revealed concentric regions of dust rings and gaps. The object's proximity and expected equilibrated state due to its old age (>20$\,$Myr) make it a superb testbed for hydrodynamical studies in direct comparison to observations. We employ two-dimensional hydrodynamical simulations of gas and multiple dust species to test whether the observed structure conforms with the presence of giant planets embedded in the disc. We then perform radiative transfer calculations of sky images, which we filter for the telescope response fo…
The Solar System gas giants are each surrounded by many moons, with at least 50 prograde satellites thought to have formed from circumplanetary material. Just like the Sun is not the only star surrounded by planets, extrasolar gas giants are likely surrounded by satellite systems. Here, we report on ALMA observations of four <40 Myr old stars with directly-imaged companions: PZ Tel, AB Pic, 51 Eri, and $κ$ And. Continuum emission at 1.3 mm is undetected for any of the systems. Since these are directly-imaged companions, there is knowledge of their temperatures, masses and locations. These allo…
The spectral energy distribution of YSES 1 b and its circumplanetary disc
SRON - Space Research Organisation Netherlands（荷兰空间研究所）；Leiden Observatory, Leiden University（莱顿天文台，莱顿大学）；Steward Observatory, The University of Arizona（斯图尔德天文台，亚利桑那大学）；Subaru Telescope, National Observatory of Japan（昴星团望远镜，日本国立天文台）；Wyant College of Optical Sciences, The University of Arizona（怀安特光学科学学院，亚利桑那大学）
Planetary Construction Zones in Occultation: Discovery of an Extrasolar Ring System Transiting a Young Sun-like Star and Future Prospects for Detecting Eclipses by Circumsecondary and Circumplanetary Disks
Circumplanetary Disk Candidate in the Disk of HD 163296 Traced by Localized Emission from Simple Organics
University of Florida（佛罗里达大学）；Leiden University（莱顿大学）；Max-Planck Institut für Extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；Università degli Studi di Milano（米兰大学）；Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange（蔚蓝海岸大学，蔚蓝海岸天文台，法国国家科学研究中心，拉格朗日实验室）；Max-Planck Institute for Astronomy (MPIA)（马克斯·普朗克天文学研究所）；Università di Bologna（博洛尼亚大学）
HD 163296盘中发现环行星盘候选者，通过简单有机物的局部发射追踪，推断行星质量上限为1.8倍木星质量。
While giant planet occurrence rates increase with stellar mass, occurrence rates of close-in super-Earths decrease. This is in contradiction to the expectation that the total mass of the planets in a system scale with the protoplanetary disc mass and hence the stellar mass. Since the snow line plays an important role in the planet formation process we examine differences in the temperature structure of protoplanetary gas discs around stars of different mass. Protoplanetary discs likely contain a dead zone at the midplane that is sufficiently cold and dense for the magneto-rotational instabilit…
We examine the migration of low mass planets in laminar protoplanetary discs, threaded by large scale magnetic fields in the dead zone that drive radial gas flows. As shown in Paper I, a dynamical corotation torque arises due to the flow-induced asymmetric distortion of the corotation region and the evolving vortensity contrast between the librating horseshoe material and background disc flow. Using simulations of laminar torqued discs containing migrating planets, we demonstrate the existence of the four distinct migration regimes predicted in Paper I. In two regimes, the migration is approxi…
We report the discovery of a circumplanetary disk (CPD) candidate embedded in the circumstellar disk of the T Tauri star AS 209 at a radial distance of about 200 au (on-sky separation of 1."4 from the star at a position angle of $161^\circ$), isolated via $^{13}$CO $J=2-1$ emission. This is the first instance of CPD detection via gaseous emission capable of tracing the overall CPD mass. The CPD is spatially unresolved with a $117\times82$ mas beam and manifests as a point source in $^{13}$CO, indicating that its diameter is $\lesssim14$ au. The CPD is embedded within an annular gap in the circ…
The discovery of substructures in protoplanetary disks with ALMA has provided us key insights on the formation of planets. However, observational constraints on the formation of rocky planets have been still sparse, especially because of the limited spatial resolution. The inner edge of so-called dead zone is one of the preferential sites of rocky planet formation. We investigate the capabilities of ALMA and ngVLA for observing a dust concentration expected at the inner edge of the dead-zone around a Herbig star. Herbig Ae/Be stars are useful laboratories for exploring the evolution of rocky g…
Gaps imaged in protoplanetary discs are suspected to be opened by planets. We compute the present-day mass accretion rates $\dot{M}_{\rm p}$ of seven hypothesized gap-embedded planets, plus the two confirmed planets in the PDS 70 disc. The accretion rates are based on disc gas surface densities $Σ_{\rm gas}$ from C$^{18}$O observations, and planet masses $M_{\rm p}$ from simulations fitted to observed gaps. Assuming accretion is Bondi-like, we find in eight out of nine cases that $\dot{M}_{\rm p}$ is consistent with the time-averaged value given by the current planet mass and system age, $M_{\…
