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STScI NRDD, 20 Oct 2005

Dynamics and Structure in Resolved Dusty Disks. Pawel Artymowicz University of Toronto. 1. Structures vs. reasons (planets,…) 2. Dust, avalanches, f IR , gas, and the calssification of disks 3. HD 141569A 4. Non-axisymmetric features without planets. STScI NRDD, 20 Oct 2005. New edge-

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STScI NRDD, 20 Oct 2005

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  1. Dynamics and Structure in Resolved Dusty Disks Pawel Artymowicz University of Toronto 1. Structures vs. reasons (planets,…) 2. Dust, avalanches, fIR, gas, and the calssification of disks 3. HD 141569A 4. Non-axisymmetric features without planets STScI NRDD, 20 Oct 2005

  2. New edge- on disk NICMOS/ HST (Schneider et al 2005)

  3. STIS/Hubble imaging (Heap et al 2000) Modeling (Artymowicz,unpubl.): parametric, axisymmetric disk cometary dust phase function Optical thickness  Dust density Radius r [AU] Height z [AU]

  4. The danger ofoverinterpretation of structure Are the PLANETS responsible for EVERYTHING we see? Are they in EVERY system? Or are they like the Ptolemy’s epicycles, added each time we need to explain a new observation? Also, do we really need a new type of particle for every bandpass [optical, sub-mm]?

  5. FEATURESin disks: (9) blobs, clumps ￭ streaks, feathers ￭ rings (axisymm) ￭ rings (off-centered) ￭ inner/outer edges ￭ disk gaps ￭ warps ￭ spirals, quasi-spirals￭ tails, extensions ￭ ORIGIN: (10) ￭ instrumental artifacts, variable PSF, noise, deconvolution etc. ￭ background/foreground obj. ￭ planets (gravity) ￭ stellar companions, flybys ￭ dust migration in gas ￭ dust blowout, avalanches ￭ episodic release of dust ￭ ISM (interstellar wind) ￭ stellar UV, wind, magnetism ￭ collective eff. (selfgravity) (Most features additionally depend on the viewing angle)

  6. FEATURES in disks: blobs, clumps ￭ streaks, feathers ￭ rings (axisymm) ￭ rings (off-centered) ￭ inner/outer edges ￭ disk gaps ￭ warps, incl. disks ￭ spirals, quasi-spirals￭ tails, extensions ￭ ORIGIN: ￭ instrumental artifacts, variable PSF, noise, deconvolution etc.

  7. FEATURES in disks: blobs, clumps ￭ streaks, feathers ￭ rings (axisymm) ￭ rings (off-centered) ￭ inner/outer edges ￭ disk gaps ￭ warps ￭ spirals, quasi-spirals￭ tails, extensions ￭ ORIGIN: ￭ background or foreground objects

  8. AB Aur : disk or no disk? Fukugawa et al. (2004) another “Pleiades”-type star no disk

  9. ? Source: P. Kalas

  10. AU Microscopii & a less inclined cousin This is a coincidentally(!) aligned background galaxy

  11. .

  12. FEATURES in disks: blobs, clumps ￭ streaks, feathers ￭ rings (axisymm) ￭ rings (off-centered) ￭ inner/outer edges ￭ disk gaps ￭ warps ￭ spirals, quasi-spirals￭ tails, extensions ￭ ORIGIN: ￭ planets (gravity)

  13. Some models of structure in dusty disks rely on too limited a physics: ideally one needs to follow: full spatial distribution, velocity distribution, and size distribution of a collisional system subject to various external forces like radiation and gas drag -- that’s very tough to do! Resultant planet depends on all this. Beta = 0.01 (monodisp.)

  14. Dangers of fitting planets to individual frames/observations: Vega has 0, 1, or 2 blobs, depending on bandpass. What about its planets? Are they wavelength-dependent too?

  15. HD 141569A is a Herbig emission star >2 x solar mass, >10 x solar luminosity, Emission lines of H are double, because they come from a rotating inner gas disk. CO gas has also been found at r = 90 AU. Observations by Hubble Space Telescope (NICMOS near-IR camera). Age ~ 5 Myr, a transitional disk Gap-opening PLANET ? So far out?? R_gap ~350AU dR ~ 0.1 R_gap

  16. Hubble Space Telescope/ NICMOS infrared camera

  17. HD 14169A disk gap confirmed by new observations (HST/ACS)

  18. HD141569+BC in V band HD141569A deprojected HST/ACS Clampin et al.

  19. Type III Outward migration of protoplanets to ~100AU or outward migration of dust to form rings and spirals required to explain the structure in transitional (5-10 Myr old) dust disks and perheps also the (12-20Myr old) Beta Pictoris-type disks

  20. DISK-PLANET interaction and migration, including outward migration It used to be just type I and II... now we study a new mode of migration: type III

  21. Migration Type I : embedded in fluid Migration Type II : more in the open (gap)

  22. Migration Type I : embedded in fluid Migration Type II : in the open (gap) Migration Type III partially open (gap)

  23. Migration: type 0 type I type II & IIb type III N-body Interaction: Gas drag + Radiation press. Resonant excitation of waves (LR) Tidal excitation of waves (LR) Corotational flows (CR) Gravity Timescale of migration: from ~1e2 yr to disk lifetime (~1e7 yr) > 1e4 yr > 1e5 yr > 1e2 - 1e3 yr > 1e5 yr (?) ……………………………………………………………………….

  24. Planets were thought to always shepherd planets…or was it the other way around? Pan opens Encke gap in A-ring of Saturn Shepherding by Prometheus and Pandora

  25. A gap-opening body in a disk: Saturn rings, Keeler gap region (width =35 km) This new 7-km satellite of Saturn was announced in May 2005. To Saturn

  26. Prometheus (Cassini view)

  27. Variable-resolution PPM (Piecewise Parabolic Method) [Artymowicz 1999] Jupiter-mass planet, fixed orbit a=1, e=0. White oval = Roche lobe, radius r_L= 0.07 Corotational region out to x_CR = 0.17 from the planet disk gap (CR region) disk

  28. Type I -- III migration Figure From: “Protostars and Planets IV (2000)”; Artymowicz (this talk). type III Time-scale (years)

  29. Simulation of a Jupiter-class planet in a constant surface density disk with soundspeed = 0.05 times Keplerian speed. PPM = Piecewise Parab. Method Artymowicz (2000), resolution 400 x 400 Although this is clearly a type-II situation (gap opens), the migration rate is NOT that of the standard type-II, which is the viscous accretion speed of the nebula.

  30. Consider a one-sided disk (inner disk only). The rapid inward migration is OPPOSITE to the expectation based on shepherding (Lindblad resonances). Like in the well-known problem of “sinking satellites” (small satellite galaxies merging with the target disk galaxies), Corotational torquescause rapid inward sinking. (Gas is trasferred from orbits inside the perturber to the outside. To conserve angular momentum, satellite moves in.)

  31. Now consider the opposite case of an inner hole in the disk. Unlike in the shepherding case, the planet rapidly migrates outwards. Here, the situation is an inward-outward reflection of the sinking satellite problem. Disk gas traveling on hairpin (half-horeseshoe) orbits fills the inner void and moves the planet out rapidly (type III outward migration). Lindblad resonances produce spiral waves and try to move the planet in, but lose with CR torques.

  32. xCR NO MIGRATION: In this frame, comoving with the planet, gas has no systematic radial velocity V = 0, r = a = semi-major axis of orbit. Symmetric horseshoe orbits, torque ~ 0 0 a r Librating Corotational (CR) region protoplanet disk Librating Hill sphere (Roche lobe) region xCR = half-width of CR region, separatrix distance

  33. SLOW MIGRATION: In this frame, comoving with the planet, gas has a systematic radial velocity V = - da/dt = -(planet migr.speed) asymmetric horseshoe orbits, torque ~ da/dt 0 a r FAST MIGRATION: CR flow on one side of the planet, disk flow on the other Surface densities in the CR region and the disk are, in general, different. Tadpole orbits, maximum torque 0 a r

  34. Saturn-mass protoplanet in a solar nebula disk (1.5 times the Minimum Nebula, PPM, Artymowicz 2003) Azimuthal angle (0-360 deg) Type III outward migration Condition for FAST migration: disk mass (in CR region) similar to planet mass. Notice a carrot-shaped bubble of “vacuum” behind the planet. Consisting of material trapped in librating orbits, it produces CR torques smaller than the matrial in front of the planet. The net CR torque powers fast migration. 1 2 3 radius

  35. Summary of type-III migration • Extremely rapid (timescale < 1000 years). CRs >> LRs, disks do not shepherd planets. Requires sufficient disk density • Direction depends on prior history, not just on disk properties. • Supersedes a much slower, standard type-II migration (&type I ??) • Migration stops on disk features (rings, edges and/or substantial density gradients.) Such edges seem natural (dead zone boundaries, magnetospheric inner disk cavities, formation-caused radial disk structure) • Offers possibility of survival of giant exoplanets at intermediate distances (0.1 - 1 AU), • ...and of terrestrial planets during the passage of a giant planet on its way to the star (last Mohican scenario) • STRUCTURE in OUTER REGIONS of dusty transitional & debris disks

  36. FEATURES in disks: blobs, clumps ￭ streaks, feathers ￭ rings (axisymm) ￭ rings (off-centered) ￭ inner/outer edges ￭ disk gaps ￭ warps ￭ spirals, quasi-spirals￭ tails, extensions ￭ ORIGIN: ￭ stellar companions, flybys

  37. Stellar flyby (of an elliptic-obit companion) explains some features of HD 141569A Augereau and Papaloizou (2003) Application of the idea to Beta Pictoris less certain...

  38. Quillen et al. (2004) HD 141569A

  39. Ardila et al (2005)Flyby+planetesimals --> dust production & outflow H/r = 0.05 H/r =0.1 LTE Linear dust prod. = 4 Mgas = 50 ME Quadratic prod.

  40. Ardila et al (2005) Flyby+plane+planetesimals No planet 5 MJ, e=0.6 planet = 4 H/r = 0.1 Mgas = 50 ME Linear dust prod. Quadratic prod.

  41. Best model, Ardila et al (2005) Beta = 4 H/r = 0.1 Mgas = 50 ME 5 MJ, e=0.6, a=100 AU planet HD 141569A

  42. Room for improvement in theory Wyatt (2005) - planetesimal evolution under seclural perturbation from an eccentric planet, initial time evolution of pericenter glow. 1. No gas drag 2. No dust 3. Planet acts on gas disk to produce spiral waves (in gas and dust) at Lindblad resonances. Ardila et al (2005) 1. Sharp outer edge at 1*pericenter distance of flyby * 2. No pre-existing dust in disk, only the dust produced after perturbation (no time for that?) 3. Single beta value, 4. No dust-dust collisions or avalanches

  43. FEATURES in disks: blobs, clumps ￭ streaks, feathers ￭ rings (axisymm) ￭ rings (off-centered) ￭ inner/outer edges ￭ disk gaps ￭ warps ￭ spirals, quasi-spirals￭ tails, extensions ￭ ORIGIN: ￭ dust migration in gas

  44. Planetary systems: stages of decreasing dustiness In the protoplanetary disks (tau) dust follows gas. Sharp features due to associated companions: stars, brown dwarfs and planets. 1 Myr These optically thin transitional disks (tau <1) must have some gas even if it's hard to detect. Warning: Dust starts to move w.r.t. gas! Look for outer rings, inner rings, gaps with or without planets. 5 Myr Pictoris 12-20 Myr These replenished dust disk are optically thin (tau<<1) and have very little gas. Sub-planetary & planetary bodies can be detected via spectroscopy, spatial distribution of dust, but do not normally expect sharp features. Extensive modeling including dust-dust collisions and radiation pressure needed

  45. Migration: Type 0 • Dusty disks: structure from gas-dust coupling (Takeuchi & Artymowicz 2001) • theory will help determine gas distribution Predicted dust distribution: axisymmetric ring Gas disk tapers off here

  46. Weak/no PAH emission Neutral (grey) scattering from s> grains Repels ISM dust Disks = Nature, not nurture! Size spectrum of dust has lower cutoff Radiative blow-out of grains (-meteoroids, gamma meteoroids) Instabilities (in disks) Radiation pressure on dust grains in disks Dust avalanches Quasi-spiral structure Orbits of stable -meteoroids elliptical Dust migrates, forms axisymmetric rings, gaps (in disks with gas) Color effects Enhanced erosion; shortened dust lifetime Short disk lifetime Age paradox

  47. FEATURES in disks: blobs, clumps ￭ streaks, feathers ￭ rings (axisymm) ￭ rings (off-centered) ￭ inner/outer edges ￭ disk gaps ￭ warps ￭ spirals, quasi-spirals￭ tails, extensions ￭ ORIGIN: ￭ dust blowout avalanches, ￭ episodic/local dust release

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