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SUMMARY:On the migration of giant mass planets in 3D disks accreting from 
 surface layers
DTSTART;VALUE=DATE-TIME:20200513T115500Z
DTEND;VALUE=DATE-TIME:20200513T121500Z
DTSTAMP;VALUE=DATE-TIME:20240704T115532Z
UID:indico-contribution-11-44@meetings.aip.de
DESCRIPTION:Speakers: Elena Lega ()\nThe classic view of a viscous disk\, 
 where viscosity is generated by strong turbulence driven by the magneto ro
 tational instability\, is challenged by modern magneto-hydrodynamic simula
 tions. Disks are probably much less viscous than previously thought. Never
 theless\, disks cannot be in-viscid\, a minimum viscosity is set for examp
 le by the so-called vertical shear instability (VSI). In addition\, disk w
 inds remove angular momentum from thin surface layers of the proto-planeta
 ry disk\, promoting  fast radial transport of gas towards the central star
  in these layers. This radial transport accounts for the observed stars' a
 ccretion rate.\nIn a classical viscous disk with radial transport correspo
 nding to  observed stellar accretion rate\, giant planets migrate towards 
 the star and easily become hot Jupiters with short orbital period.  Howeve
 r\, the majority of observed giant planets have distances of 1-3AU from th
 eir parent star.\nThis contradiction has been investigated looking at a va
 riety of migrations mechanisms\, but no general mechanism to reduce planet
  migration has been found.\nThe new paradigm of disks  with small bulk vis
 cosity and fast radial advection in surface offers a different perspective
  of the problem.\nConsequently\, we perform 3D numerical simulations using
  the FARGOCA code. We simulate the effect of disk wind by imposing a loss 
 of angular momentum generating a desired mass flux  in a thin surface laye
 r.\nWe show that  planets migration is only marginally affected by the fas
 t gas in the thin layers and that the migration speed is mainly regulated 
 by the bulk viscosity of the disk. However\, the migration rate measured w
 ith a bulk viscosity of alpha=1.e-4 (typically of the order of that genera
 ted by the VSI in the outer disk)  is still too fast to understand  the ob
 served radial distribution of extra-solar planets.  Decreasing further the
  viscosity seems necessary for the understanding of the  observations.\n\n
 https://meetings.aip.de/event/1/contributions/44/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/44/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Non-equilibrium dynamics of massive embedded planetary systems
DTSTART;VALUE=DATE-TIME:20200513T124500Z
DTEND;VALUE=DATE-TIME:20200513T130500Z
DTSTAMP;VALUE=DATE-TIME:20240704T115532Z
UID:indico-contribution-11-52@meetings.aip.de
DESCRIPTION:Speakers: Thomas Rometsch (University of Tübingen)\nRecently\
 , young planets with masses around $10\\\,M_\\text{Jupiter}$ which are sti
 ll embedded in a disk have been observed\, e.g. in the PDS 70 system. At t
 his mass range\, the planet-disk interaction is non-linear and the planets
  are attributed with having carved the observed gap into their parent disk
 . One possible scenario for the formation of large gaps is outward migrati
 on in 2:1 mean motion resonance (MMR) where the inner planet is more massi
 ve than the outer one. This process is known to strongly excite the planet
 s' eccentricities which in turn leads to eccentric gaps. The latter could 
 be an observable feature of such systems. \n\nWe perform 2D\, vertically i
 ntegrated hydrodynamics simulations to study the migration and dynamics of
  the embedded planetary system employing a viscous $\\alpha$-disk model. T
 o avoid artificial wave-damping boundary conditions we choose large outer 
 disk radii and work in the center of mass frame of the planetary system. I
 n addition to the often used locally isothermal equation of state\, we run
  simulations with radiative cooling\, viscous heating and irradiation from
  the star from which temperature distributions in the perturbed disk can b
 e extracted.\n\nThe simulations exhibit the expected smooth 2:1 MMR outwar
 d migration. For sufficiently high surface densities of the order of the m
 inimum mass solar nebula we additionally observe epochs of fast migration.
  During a sequence which we call migration jumps\, the outer planet underg
 oes fast outward migration traveling tens of au outward. It stays at the l
 arge distance for some kyr before returning back into the 2:1 MMR via fast
  inward migration. The whole sequence only takes 10-20 kyr. Meanwhile the 
 inner planet remains relatively unaffected. A migration jump causes strong
  perturbations in the disk including pronounced spiral arms and asymmetric
  features including vortices and mass accumulation in the Lagrange points 
 inside the gap region. The latter might be an observational indication for
  this process.\n\nDue to the large mass of the embedded planets\, the feat
 ures created in the disk are strong and synthetic observations of the simu
 lations might help to identify whether these mechanisms are at play in the
  disks we observe. In addition\, migration jumps of massive planets can be
  expected to cause strong scattering of dust particles and small bodies in
  the radial range on which the jumps occur. Thereby\, they might play an i
 mportant role for the dust and small body distribution in the earlier stag
 es of the systems lifetime.\n\nhttps://meetings.aip.de/event/1/contributio
 ns/52/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/52/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Giant planet migration in low-viscosity disks
DTSTART;VALUE=DATE-TIME:20200513T122000Z
DTEND;VALUE=DATE-TIME:20200513T124000Z
DTSTAMP;VALUE=DATE-TIME:20240704T115532Z
UID:indico-contribution-11-40@meetings.aip.de
DESCRIPTION:Speakers: Alessandro Morbidelli (OCA)\nGiant planet migration 
 (a.k.a. Type-II migration) should occur with a migration speed proportiona
 l to the disk's viscosity. This has been verified for alpha-disks with alp
 ha>1.e-4 (Robert et al.\, 2018). But what happens in disks with vanishing 
 viscosity? Does Type-II migration stalls? A variety of behaviors have been
  observed in the literature for migration in low-viscosity disks. Migratio
 n seems to be very stochastic\, with very fast migration episodes (e.g. Mc
 Nally et al.\, 2018).   However\, most simulations so far have been conduc
 ted in 2D disks. We find that low-viscosity 3D disks are much more stable 
 than 2D disks of equivalent viscosity when they are perturbed by a planet\
 , because they are submitted to the constraint of vertical hydrostatic equ
 ilibrium. Consequently giant planet migration in 3D disks behaves more reg
 ularly. Nevertheless\, the presence of vortex formed at the outer edge of 
 the gap opened by the planet affects the planet evolution. We have investi
 gated in details the influence of a vortex on planet migration and on the 
 growth of the planet's orbital eccentricity as well as the feedback of the
  eccentricity on migration.\n\nhttps://meetings.aip.de/event/1/contributio
 ns/40/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/40/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Observational signatures of tightly-wound spirals driven by buoyan
 cy resonance
DTSTART;VALUE=DATE-TIME:20200513T113000Z
DTEND;VALUE=DATE-TIME:20200513T115000Z
DTSTAMP;VALUE=DATE-TIME:20240704T115532Z
UID:indico-contribution-11-25@meetings.aip.de
DESCRIPTION:Speakers: Jaehan Bae (Carnegie Institution of Washington)\nSpi
 ral waves are one of the most fundamental outcomes of planet-disk interact
 ion. In addition to the well-known Lindblad resonance\, buoyancy resonance
 \, which occurs when the vertical buoyancy frequency of disk gas matches w
 ith an integer multiple of the planet's orbital frequency\, can excite spi
 ral waves. Based on three-dimensional global hydrodynamic simulations and 
 synthetic ALMA line observations\, we will show that buoyancy spirals can 
 produce observable kinematic signatures. One of the main characteristics o
 f buoyancy spirals is their tightly-wound morphology (i.e.\, a small pitch
  angle compared with Lindblad spirals). The strength and observability of 
 buoyancy spirals depend sensitively on the disk thermodynamics. This highl
 ights the importance of using more realistic thermodynamics in hydrodynami
 c simulations.\n\nhttps://meetings.aip.de/event/1/contributions/25/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/25/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Radiative effects in protoplanetary disks: planet-disk interaction
DTSTART;VALUE=DATE-TIME:20200513T075000Z
DTEND;VALUE=DATE-TIME:20200513T081000Z
DTSTAMP;VALUE=DATE-TIME:20240704T115532Z
UID:indico-contribution-11-38@meetings.aip.de
DESCRIPTION:Speakers: Alexandros Ziampras (University of Tuebingen)\nRecen
 t ALMA observations revealed concentric annular structures in several youn
 g\, class-II objects. Some have been modeled numerically with a single emb
 edded planet assuming a locally isothermal equation of state\, a method of
 ten used in the irradiation-dominated outer disk regions. We compare local
 ly isothermal and radiative disks similar to HD 163296 and AS 209 with emb
 edded planets and\nshow that the disk thermodynamics can impact the number
  of rings and the contrast of spirals produced by a planet. Radiative effe
 cts can suppress features visible in locally isothermal simulations. These
  results suggest the need for multiple planets to explain the ring-rich st
 ructures in such systems.\n\nhttps://meetings.aip.de/event/1/contributions
 /38/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/38/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Investigating a new paradigm for type II migration
DTSTART;VALUE=DATE-TIME:20200513T072500Z
DTEND;VALUE=DATE-TIME:20200513T074500Z
DTSTAMP;VALUE=DATE-TIME:20240704T115532Z
UID:indico-contribution-11-60@meetings.aip.de
DESCRIPTION:Speakers: Dylan Kloster (OCA)\nUnderstanding the origins and d
 ynamics of massive planets during the planet-formation process is essentia
 l to understanding how the structures of individual planetary systems came
  to be.  Massive planets have the ability to open gaps in their host disk\
 , and the radial movements of these gap-opening planets is typically refer
 red to as type II migration.  In the classical view\, a protoplanetary dis
 k accretes onto its star on a viscous timescale\, carrying this gap inward
 s with the planet moving with the gap.  This theory assumes that the plane
 t remains in a state of quasi-equilibrium at the center of the gap. Howeve
 r\, a non-zero torque from the disk must be applied to the planet for it t
 o move radially\, meaning the planet is not necessarily located at equilib
 rium.  This implies that while the gap is in motion\, and the planet is be
 ing dragged along with it\, the location of the planet is not necessarily 
 at the center of the gap.  In addition\, if we define the location of the 
 gap center to be the radial position of a planet with a fixed orbit (i.e.\
 , a non-migrating planet)\, we also consider the possibility that the equi
 librium position of the planet differs from this center.  We explore these
  properties involving the gap-planet interaction of an evolving protoplane
 tary disk with 2D simulations using the FargOCA hydrodynamics code.  We ac
 complish this by fixing the orbital radius of a massive planet ($M_p/M_* =
  0.001$) until its disk has reached a steady state.  At this stage we rele
 ase the planet from its fixed orbit\, and allow it to migrate freely.  We 
 then analyze the planet's displacement from equilibrium\, as well as its d
 isplacement from the gap center\, varying disk properties such as aspect r
 atio and viscosity\, and explore their effects on the planet migration rat
 e.\n\nhttps://meetings.aip.de/event/1/contributions/60/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/60/
END:VEVENT
BEGIN:VEVENT
SUMMARY:40 years of disk-planet interaction: some new developments in an o
 ld problem
DTSTART;VALUE=DATE-TIME:20200513T070000Z
DTEND;VALUE=DATE-TIME:20200513T072000Z
DTSTAMP;VALUE=DATE-TIME:20240704T115532Z
UID:indico-contribution-11-8@meetings.aip.de
DESCRIPTION:Speakers: Roman Rafikov (University of Cambridge)\nGravitation
 al coupling between protoplanetary disks and embedded planets is an old pr
 oblem ascending to the seminal studies of Goldreich & Tremaine (1980) and 
 Lin & Papaloizou (1979). It is widely recognized as playing a key role in 
 many areas of exoplanetary science: determination of the planetary archite
 ctures\, disk evolution\, planetary accretion\, and so on. In this talk I 
 will describe several key theoretical advances that took place in this fie
 ld in recent years. They provide a better understanding of the ways in whi
 ch density waves get excited in disks by planets\, how they propagate thro
 ugh the disk\, and how they dissipate\, linearly and non-linearly\, drivin
 g global disk evolution. I will particularly focus on recent advances in i
 ncorporating realistic disk thermodynamics in studies of disk-planet coupl
 ing\, their impact on the numerical studies of this phenomenon\, and the o
 bservational manifestations of massive planets in protoplanetary disks\, i
 ncluding both scattered light imaging and recent ALMA observations of fine
  structures in disks.\n\nhttps://meetings.aip.de/event/1/contributions/8/
LOCATION:Leibniz Institute for Astrophysics Potsdam (AIP) Lecture Hall
URL:https://meetings.aip.de/event/1/contributions/8/
END:VEVENT
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