1 / 23

Dust Dynamics in Debris Gaseous Disks

Dust Dynamics in Debris Gaseous Disks. Dynamics of Dust - gas drag - radiation 2. Estimate of Gas Mass 3. Dust Disk Structure Formed by a Planet in a Gas Disk. Taku Takeuchi (Kobe Univ., Japan). Gas Drag on a Dust Grain. Epstein drag law Stopping time. Small Grains:.

Download Presentation

Dust Dynamics in Debris Gaseous Disks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Dust Dynamics in Debris Gaseous Disks • Dynamics of Dust • - gas drag • - radiation • 2. Estimate of Gas Mass • 3. Dust Disk Structure Formed by a Planet in a Gas Disk Taku Takeuchi (Kobe Univ., Japan)

  2. Gas Drag on a Dust Grain • Epstein drag law • Stopping time

  3. Small Grains: • Due to strong gas drag, grains co-rotate with the gas, which orbits with sub-Keplerian velocity. sub-Kepler

  4. Large Grains: • Grains orbit with the Keplerian velocity, which is faster than the gas Kepler head-wind

  5. at 100 AU tmin Orbital Decay Rate Adachi et al. 1976; Weidenschilling 1977 • As the gas mass decreases, • tmin=const., but the sizeat tmin decreases • Even if the gas mass is as small as 0.01Mearth, grains of 1-10mm rapidly fall tstop=torb

  6. Radiation Pressure (Optically thin disk) Burns et al. 1979; Artymowicz 1988 • RP reduces the central star’s gravity reduction factor:

  7. slower than gas fair-wind headwind faster than gas Direction of Grains’ Drift Takeuchi & Artymowicz 2001 • Size segregation • Dust clumping at the edge of the gas disk

  8. pressure Increase in the dust density radius Clumping Instability Klahr & Lin 2005 • Gas temperature = Dust temperature

  9. 100AU 10AU 1AU MMSN model Force Ratio (Fph / FRP) Other Radiation Effects • Poynting-Robertson drag • much smaller than gas drag • Photophoresis (Krauss & Wurm 2005) cold hot

  10. at 100 AU Timescales • In a gas disk with Mg>Mluna, gas drag dominates the dust evolution

  11. Gas free disk 1000AU 100AU Estimate of the Gas Mass (w/o planets) • b Pic (Thébault & Augereau 2005) dust disk Planetesimal disk

  12. bPic(Thébault & Augereau 2005) • upper limit: Mg<0.4Mearth • H2 emission (ISO): 50Mearth (Thi et al. 2001) • H2 absorption (FUSE): <0.1Mearth (Lacavelier Des Etangs et al. 2001) • NaI emission : 0.1Mearth (Brandeker et al. 2004) Gaseous disk (40Mearth )

  13. b meteoroids spiral wave HD 141569 (Ardila et al. 2005) • Scattered light from b meteoroids (s~1mm) • Mg<50Mearth • Distribution of b meteoroids shows a spiral pattern, because it traces the distribution of planetesimals. • CO emission: Mg<60Mearth(Zuckerman et al. 1995) Stellar flyby Planetesimal disk

  14. gas disk planetesimal disk HR 4796 (Takeuchi & Artymowicz 2001) • Mg~4Mearth • CII absorption: Mg<1Mearth(Chen & Kamp 2004) Telesco et al. (2000)

  15. Gas + Planets • Resonant trapping • large grains (orbit faster than the gas): • drift inward • trapped at exterior resonances (Weidenschilling & Davis 1985) • small grains (orbit slower than the gas): • drift outward • trapped at interior resonances (Doi & Takeuchi, in prep.)

  16. Complications by Gas Disturbances • Gap • Spiral waves • Turbulences Lubow et al. 1999

  17. j+1:j j+2:j+1 Gap • Gap opening time at j+1:j LR (Goldreich & Tremaine 1980) • Timescale to form resonant structure (Weidenschilling & Davis 1985)

  18. 1Mearth 1MJupiter Timescale Timescale j=10 j=3 j j Gap Opening / Resonant Trapping Timescales • Resonant trapping probably does not form prominent structure before gap opening

  19. Gas density Bryden et al. 2000 Grain Accumulation at the Gap Edges

  20. Spiral Waves • Planet’s gravity and /or spiral waves may distort the dust rings. clumps? Lubow et al. 1999

  21. Turbulence • Optically thin disks are probably unstable against MRI (Sano et al. 2000) • Turbulence inhibits planets from opening a gap • Can resonant trapping occur in turbulent disks? A 30 Mearth planet cannot open a gap in a turbulent disk (Nelson & Papaloizou 2004)

  22. Type I Migration • can be neglected • Mp=30Mearth, at 100AU, Mg=30Mearth, • tmig~1Gyr (Tanaka et al. 2002)

  23. Summary / Unresolved Questions • Gas of a lunar mass can dominate the orbital evolution of the dust • Gas drag can form structure in dust disks without any planets or companions • Gas mass can be estimated from the structure of the dust disk (if there is no planet) • What structure does a planet form in a gas disk?

More Related