Impact of embedded circumplanetary winds on the circumstellar disk: I. Reshaping the local accretion environment
Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez（阿道夫·伊巴涅斯大学工程与科学学院）；Data Observatory Foundation（数据天文台基金会）；Departamento de Astronomía, Universidad de Chile（智利大学天文学系）
Danilo Sepúlveda-Rojas, Pablo Benítez-Llambay, Simon Casassus
The existence of winds is among the uncertainties related to the growth of giant planets. Such circumplanetary outflows have been proposed to explain kinematic and chemical structures in protoplanetary disks. We investigate the immediate impact of circumplanetary outflows on the circumstellar disk environment, the planetary vicinity, and planetary growth. We performed three-dimensional hydrodynamic simulations using \texttt{FARGO3D}, implementing a parametric wind launched from the vicinity of an embedded planet. Although the imposed configurations for the outflows do not significantly alter the global structure of the disk, they do substantially redistribute material in the vicinity of the embedded planet. In particular, the wind redirects accretion flows from polar to equatorial latitudes, resulting in variable accretion patterns over time. Although the mass accretion rate variations depend on the efficiency of the outflows, their presence diminishes the accretion rate over time and the total mass reservoir within the Hill sphere and the planet's direct vicinity, potentially slowing or limiting planetary growth.
We present long baseline Atacama Large Millimeter/submillimeter Array (ALMA) observations of the 870$\,μ$m dust continuum emission and CO (3-2) from the protoplanetary disk around the Herbig Ae/Be star HD 100546, which is one of the few systems claimed to have two young embedded planets. These observations achieve a resolution of 4 au (3.8 mas), an rms noise of 66$μ$Jy/beam, and reveal an asymmetric ring between $\sim$20-40 au with largely optically thin dust continuum emission. This ring is well fit by two concentric and overlapping Gaussian rings of different widths and a Vortex. In addition…
We carried out 3D dust+gas radiative hydrodynamic simulations of forming planets. We investigated a parameter grid of Neptune-, Saturn-, Jupiter-, and 5 Jupiter-mass planets at 5.2, 30, 50 AU distance from their star. We found that the meridional circulation \citep{Szulagyi14,FC16} drives a strong vertical flow for the dust as well, hence the dust is not settled in the midplane, even for mm-sized grains. The meridional circulation will deliver dust and gas vertically onto the circumplanetary region, efficiently bridging over the gap. The Hill-sphere accretion rates for the dust are $\sim10^{-8…
There are growing amount of very high-resolution polarized scattered light images of circumstellar disks. Nascent giant planets planets are surrounded by their own circumplanetary disks which may scatter and polarize both the planetary and stellar light. Here we investigate whether we could detect circumplanetary disks with the same technique and what can we learn from such detections. Here we created scattered light mock observations at 1.245 microns (J band) for instruments like SPHERE and GPI, for various planetary masses (0.3, 1.0, 5.0, 10.0 $\rm{M_{Jup}}$), disk inclinations (90, 60, 30, …
We present a detailed analysis for a subset of the high resolution (~35 mas, or 5 au) ALMA observations from the Disk Substructures at High Angular Resolution Project (DSHARP) to search for faint 1.3 mm continuum emission associated with dusty circumplanetary material located within the narrow annuli of depleted emission (gaps) in circumstellar disks. This search used the Jennings et al. (2020) $\tt{frank}$ modeling methodology to mitigate contamination from the local disk emission, and then deployed a suite of injection-recovery experiments to statistically characterize point-like circumplane…
We describe a model for the long term evolution of a circumplanetary disk that is fed mass from a circumstellar disk and contains regions of low turbulence (dead zones). We show that such disks can be subject to accretion driven outbursts, analogous to outbursts previously modeled in the context of circumstellar disks to explain FU Ori phenomena. Circumplanetary disks around a proto-Jupiter can undergo outbursts for infall accretion rates onto the disks in the range ~10^{-9} to 10^{-7} M_sun/yr, typical of accretion rates in the T Tauri phase. During outbursts, the accretion rate and disk lumi…
We present ALMA observations of the GQ Lup system, a young Sun-like star with a substellar mass companion in a wide-separation orbit. These observations of 870 $μ$m continuum and CO J=3-2 line emission with beam size $\sim0.3''$ ($\sim45$ AU) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The circumprimary dust disk is compact with a FWHM of $59\pm12$ AU, while the gas has a larger extent with a characteristic radius of $46.5\pm1.8$ AU. By forward-modeling the velocity field of th…
We investigate the properties of circumplanetary discs formed in three-dimensional, self-gravitating radiation hydrodynamical models of gas accretion by protoplanets. We determine disc sizes, scaleheights, and density and temperature profiles for different protoplanet masses, in solar nebulae of differing grain opacities. We find that the analytical prediction of circumplanetary disc radii in an evacuated gap (R_Hill/3) from Quillen & Trilling (1998) yields a good estimate for discs formed by high mass protoplanets. The radial density profiles of the circumplanetary discs may be described by p…
Accretion disks in binary systems can exhibit a tilt instability, arising from the interaction between components of the tidal potential and dissipation. Using a linear analysis, we show that the aspect ratios and outer radii of circumplanetary disks provide favorable conditions for tilt growth. We quantify the growth rate of the instability using particle-based ({\sc phantom}) and grid-based ({\sc athena++}) hydrodynamic simulations. For a disk with outer aspect ratio $H/r \simeq 0.1$, initially moderate tilts double on a time scale of about 15-30 binary orbits. Our results imply that detache…
The large icy moons of Jupiter formed in a circumplanetary disk (CPD). CPDs are fed by infalling circumstellar gas and dust which may be shock-heated upon accretion or sublimated while passing through an optically thin gap. Accreted material is then either incorporated into moons, falls into the planet, or is lost beyond the disk edge on relatively short timescales. If ices are sublimated during accretion onto the CPD we know there must be sufficient time for them to recondense or moons such as Ganymede or Callisto could not form. The chemical timescale to form sufficiently icy solids places a…
Circumplanetary disks regulate the late accretion to the giant planet and serve as the birthplace for satellites. Understanding their characteristics via simulations also helps to prepare for their observations. Here we study disks around 1, 3, 5, 10 $\mathrm{M_{Jup}}$ planets with three dimensional, global radiative hydrodynamic simulations with sub-planet peak resolution, and various planetary temperatures. We found that as the 1 $\mathrm{M_{Jup}}$ planet radiates away its formation heat, the circumplanetary envelope transitions to a disk between $T_p = 6000$ K and 4000 K. In the case of 3-1…
The effects of viscosity on the circumplanetary disks residing in the vicinity of protoplanets are investigated through two-dimensional hydrodynamical simulations with the shearing sheet model. We find that viscosity can affect properties of the circumplanetary disk considerably when the mass of the protoplanet is $M_p \lesssim 33M_\oplus$, where $M_\oplus$ is the Earth mass. However, effects of viscosity on the circumplanetary disk are negligibly small when the mass of the protoplanet $M_p \gtrsim 33M_\oplus$. We find that when $M_p \lesssim 33M_\oplus$, viscosity can disrupt the spiral struc…
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…
Using radiation hydrodynamics simulations, we explore the evolution of circumplanetary disks around wide-orbit proto-gas giants. At large distances from the star (~100 AU), gravitational instability followed by disk fragmentation can form low-mass substellar companions (massive gas giants and/or brown dwarfs) that are likely to host large disks. We examine the initial evolution of these subdisks and their role in regulating the growth of their substellar companions, as well as explore consequences of their interactions with circumstellar material. We find that subdisks that form in the context…
Circumplanetary disks can be found around forming giant planets, regardless of whether core accretion or gravitational instability built the planet. We carried out state-of-the-art hydrodynamical simulations of the circumplanetary disks for both formation scenarios, using as similar initial conditions as possible to unveil possible intrinsic differences in the circumplanetary disk mass and temperature between the two formation mechanisms. We found that the circumplanetary disks mass linearly scales with the circumstellar disk mass. Therefore, in an equally massive protoplanetary disk, the circ…
It is believed that satellites of giant planets form in circumplanetary disks. Many of the previous contributions assumed that their formation process proceeds similarly to rocky planet formation, via accretion of the satellite seeds, called satellitesimals. However, the satellitesimal formation itself poses a nontrivial problem as the dust evolution in the circumplanetary disk is heavily impacted by fast radial drift and thus dust growth to satellitesimals is hindered. To address this problem, we connected state-of-the-art hydrodynamical simulations of a circumplanetary disk around a Jupiter-…
The luminosity of young giant planets can inform about their formation and accretion history. The directly imaged planets detected so far are consistent with the "hot-start" scenario of high entropy and luminosity. If nebular gas passes through a shock front before being accreted into a protoplanet, the entropy can be substantially altered. To investigate this, we present high resolution, 3D radiative hydrodynamic simulations of accreting giant planets. The accreted gas is found to fall with supersonic speed in the gap from the circumstellar disk's upper layers onto the surface of the circumpl…
PDS70 is a unique system in which two protoplanets, PDS70b and c, have been discovered within the dust-depleted cavity of their disk, at $\sim$22 and 34au respectively, by direct imaging at infrared wavelengths. Subsequent detection of the planets in the H$α$ line indicates that they are still accreting material through circumplanetary disks. In this Letter, we present new Atacama Large Millimeter/submillimeter Array (ALMA) observations of the dust continuum emission at 855$μ$m at high angular resolution ($\sim$20mas, 2.3au) that aim to resolve the circumplanetary disks and constrain their dus…
Discs around young planets, so-called circumplanetary discs (CPDs), are essential for planet growth, satellite formation, and planet detection. We study the millimetre and centimetre emission from accreting CPDs by using the simple $α$ disc model. We find that it is easier to detect CPDs at shorter radio wavelengths (e.g. $λ\lesssim$ 1 mm). For example, if the system is 140 pc away from us, deep observations (e.g. 5 hours) at ALMA Band 7 (0.87 mm) are sensitive to as small as 0.03 lunar mass of dust in CPDs. If the CPD is around a Jupiter mass planet 20 AU away from the host star and has $α\le…
We present Karl G. Jansky Very Large Array (VLA) observations of the 7 mm continuum emission from the disk surrounding the young star LkCa 15. The observations achieve an angular resolution of 70 mas and spatially resolve the circumstellar emission on a spatial scale of 9 AU. The continuum emission traces a dusty annulus of 45 AU in radius that is consistent with the dust morphology observed at shorter wavelengths. The VLA observations also reveal a compact source at the center of the disk, possibly due to thermal emission from hot dust or ionized gas located within a few AU from the central s…
<abridged> The large relative sizes of circumstellar and circumplanetary disks imply that they might be seen in eclipse in stellar light curves. We estimate that a survey of ~10^4 young (~10 Myr old) post-accretion pre-MS stars monitored for ~10 years should yield at least a few deep eclipses from circumplanetary disks and disks surrounding low mass companion stars. We present photometric and spectroscopic data for a pre-MS K5 star (1SWASP J140747.93-394542.6), a newly discovered ~0.9 Msun member of the ~16 Myr-old Upper Cen-Lup subgroup of Sco-Cen at a kinematic distance of 128 pc. SuperWASP …
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。
The identification of on-going planet formation requires the finest angular resolutions and deepest sensitivities in observations inspired by state-of-the-art numerical simulations. Hydrodynamic simulations of planet-disk interactions predict the formation of circumplanetary disks (CPDs) around accreting planetary cores. These CPDs have eluded unequivocal detection -their identification requires predictions in CPD tracers. In this work, we aim to assess the observability of embedded CPDs with ALMA as features imprinted in the gas kinematics. We use 3D Smooth Particle Hydrodynamic (SPH) simulat…
Detection of forming planets means detection of the circumplanetary disk (CPD) in reality, since the planet is still surrounded by a disk at this evolutionary stage. Yet, no comprehensive CPD modeling was done in near-infrared wavelengths, where high contrast imaging is a powerful tool to detect these objects. We combined 3D radiative hydrodynamic simulations of various embedded planets with RADMC-3D radiative transfer post-processing that includes scattering of photons on dust particles. We made synthetic images for VLT NaCo/ERIS in the Ks, L', M' bands as well as examined the spectral energy…
We present mock observations of forming planets with ALMA. The possible detections of circumplanetary disks (CPDs) were investigated around planets of Saturn, 1, 3, 5, and 10 Jupiter-masses that are placed at 5.2 AU from their star. The radiative, three dimensional hydrodynamic simulations were then post-processed with RADMC3D and the ALMA Observation Simulator. We found that even though the CPDs are too small to be resolved, they are hot due to the accreting planet in the optically thick limit, therefore the best chance to detect them with continuum observations in this case is at the shortes…
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…
Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 10^19 kg of sub-micron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at approximately 6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the d…
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 tr…
Mid-infrared imaging traces the sub-micron and micron sized dust grains in protoplanetary disks and it offers constraints on the geometrical properties of the disks and potential companions, particularly if those companions have circumplanetary disks. We use the VISIR instrument and its upgrade NEAR on the VLT to take new mid-infrared images of five (pre-)transition disks and one circumstellar disk with proposed planets and obtain the deepest resolved mid-infrared observations to date in order to put new constraints on the sizes of the emitting regions of the disks and the presence of possible…
We use three dimensional hydrodynamical simulations to show that a highly misaligned accretion disk around one component of a binary system can exhibit global Kozai-Lidov cycles, where the inclination and eccentricity of the disk are interchanged periodically. This has important implications for accreting systems on all scales, for example, the formation of planets and satellites in circumstellar and circumplanetary disks, outbursts in X-ray binary systems and accretion on to supermassive black holes.
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, $M_{\…
Planets are often invoked as the cause of inferred gaps or inner clearings in transition disks. These putative planets would interact with the remnant circumstellar disk, accreting gas and generating substantial luminosity. Here I explore the expected appearance of accreting protoplanets at a range of evolutionary states. I compare synthetic spectral energy distributions with the handful of claimed detections of substellar-mass companions in transition disks. While observed fluxes of candidate companions are generally compatible with accreting protoplanets, challenges remain in reconciling the…
The detection of moons orbiting extrasolar planets ("exomoons") has now become feasible. Once they are discovered in the circumstellar habitable zone, questions about their habitability will emerge. Exomoons are likely to be tidally locked to their planet and hence experience days much shorter than their orbital period around the star and have seasons, all of which works in favor of habitability. These satellites can receive more illumination per area than their host planets, as the planet reflects stellar light and emits thermal photons. On the contrary, eclipses can significantly alter local…
A Formation-Stage Bottleneck for Exomoons around Close-in Rocky Planets
Chengdu University of Technology（成都理工大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）；University of Zurich（苏黎世大学）；Sun Yat-sen University（中山大学）；Institute of Geochemistry, Chinese Academy of Sciences（中国科学院地球化学研究所）
(Pre-)transitional disks show gaps and cavities that can be related with on-going planet formation. According to theory, young embedded planets can accrete material from the circumplanetary and circumstellar disks, so that they could be detected in accretion tracers, like the H$_α$ emission line. In this work, we present spectral angular differential imaging AO-assisted observations of five (pre-)transitional disks obtained with SPHERE/ZIMPOL at the Very Large Telescope (VLT). They were obtained in the H$_α$ line and the adjacent continuum. We have combined spectral and angular differential im…
We present two methods to determine an exomoon's sense of orbital motion (SOM), one with respect to the planet's circumstellar orbit and one with respect to the planetary rotation. Our simulations show that the required measurements will be possible with the European Extremely Large Telescope (E-ELT). The first method relies on mutual planet-moon events during stellar transits. Eclipses with the moon passing behind (in front of) the planet will be late (early) with regard to the moon's mean orbital period due to the finite speed of light. This "transit timing dichotomy" (TTD) determines an exo…
PDS 70b is a recently discovered and directly imaged exoplanet within the wide ($\gtrsim$40 au) cavity around PDS 70 (Keppler et al. 2018, Müller et al. 2018). Ongoing accretion onto the central star suggests that accretion onto PDS 70b may also be ongoing. We present the first high contrast images at H$α$ (656 nm) and nearby continuum (643 nm) of PDS 70 utilizing the MagAO system. The combination of these filters allows for the accretion rate of the young planet to be inferred, as hot infalling hydrogen gas will emit strongly at H$α$ over the optical continuum. We detected a source in H$α$ at…
Within the general framework of core-nucleated accretion theory of giant planet formation, the conglomeration of massive gaseous envelopes is facilitated by a transient period of rapid accumulation of nebular material. While the concurrent buildup of angular momentum is expected to leave newly formed planets spinning at near-breakup velocities, Jupiter and Saturn, as well as super-Jovian long-period extrasolar planets, are observed to rotate well below criticality. In this work, we demonstrate that the large luminosity of a young giant planet simultaneously leads to the generation of a strong …
We present 3D MHD simulations of the wind-wind interactions between a solar type star and a short period hot Jupiter exoplanet. This is the first such simulation in which the stellar surface evolution is studied in detail. In our simulations, a planetary outflow, based on models of FUV evaporation of the exoplanets upper atmosphere, results in the build-up of circumstellar and circumplanetary material which accretes onto the stellar surface in a form of coronal rain, in which the rain is HJ wind material falling onto the stellar surface. We have conducted a suite of mixed geometry high resolut…
The atmospheres and accretion disks of planetary-mass and substellar companions provide an unprecedented look into planet and moon formation processes, most notably the frequency and lifetime of circumplanetary disks. In our ongoing effort to leverage the extraordinary sensitivity of the Spitzer/Infrared Array Camera (IRAC) at 3.6, 4.5, 5.8, and 8.0 $μ$m to study wide planetary-mass and substellar companions near the diffraction limit, we present point-spread function (PSF) fitting photometry of archival Spitzer/IRAC images for nine stars (G0 to M4+M7) in nearby star-forming regions or stellar…
In this work we pose the possibility that, at an early stage, the migration of a proto--giant planet caused by the presence of a gaseous circumstellar disk could explain the continuous feeding of small bodies into its orbit. Particularly, we study the probability of capture and permanence in co--orbital resonance of these small bodies, as planets of diverse masses migrate by interaction with the gaseous disk, and the drag induced by this disk dissipates energy from these small objects, making capture more likely. Also, we study the relevance of the circumplanetary disk, a structure formed clos…
In the core-accretion model the nominal runaway gas-accretion phase brings most planets to multiple Jupiter masses. However, known giant planets are predominantly Jupiter-mass bodies. Obtaining longer timescales for gas accretion may require using realistic equations of states, or accounting for the dynamics of the circumplanetary disk (CPD) in low-viscosity regime, or both. Here we explore the second way using global, three-dimensional isothermal hydrodynamical simulations with 8 levels of nested grids around the planet. In our simulations the vertical inflow from the circumstellar disk (CSD)…
PDS 70b is the most robustly detected young planet imaged in the gap of a transition disk so far, found at a separation of ~195 mas (~22 au) from its host star and at a position angle of about 155 deg. This system is therefore a unique laboratory to characterize the properties of young planetary systems at the stage of their formation. We aim to trace direct and indirect imprints of PDS 70b on the gas and dust emission of the circumstellar disk in order to study the properties of this ~5 Myr young planetary system. We obtained ALMA band 7 observations of PDS 70 in dust continuum and $^{12}CO$ …
High-contrast imaging in the visible and near-infrared (VIS/NIR) has revealed the presence of a plethora of substructures in circumstellar disks (CSDs). One of the most commonly observed substructures are concentric gaps that may hint at the presence of embedded forming planets. However, direct detections of them are rare, and thus ambiguity regarding the origin of most gap features remains. The aim of this study is to investigate the capabilities of high-contrast VIS/NIR imaging of directly detecting and characterizing low-mass giant planets in gaps. To this end, a grid of models of protoplan…
Planets form in young circumstellar disks called protoplanetary disks. However, it is still difficult to catch planet formation in-situ. Nevertheless, from recent ALMA/SPHERE data, encouraging evidence of the direct and indirect presence of embedded planets has been identified in disks around young stars: co-moving point sources, gravitational perturbations, rings, cavities, and emission dips or shadows cast on disks. The interpretation of these observations needs a robust physical framework to deduce the complex disk geometry. In particular, protoplanetary disk models usually assume the gas p…
Sulphur-bearing volatiles are observed to be significantly depleted in interstellar and circumstellar regions. This missing sulphur is postulated to be mostly locked up in refractory form. With ALMA we have detected sulphur monoxide (SO), a known shock tracer, in the HD 100546 protoplanetary disk. Two rotational transitions: $J=7_{7}-6_{6}$ (301.286 GHz) and $J=7_8-6_7$ (304.078 GHz) are detected in their respective integrated intensity maps. The stacking of these transitions results in a clear 5$σ$ detection in the stacked line profile. The emission is compact but is spectrally resolved and t…
