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Planet and Gaps in the disk

Planet and Gaps in the disk. Hwihyun Kim Feb. 8 2006. PAPERS. Forrest, W. J., et al., 2004, ApJS, 154, 443 “Mid-IR spectroscopy of disks around classical T Tauri stars” Quillen, A. C., et al., 2004, ApJL, 612, L137 “On the planet and the disk of CoKu Tauri/4”

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Planet and Gaps in the disk

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  1. Planet and Gaps in the disk Hwihyun Kim Feb. 8 2006

  2. PAPERS • Forrest, W. J., et al., 2004, ApJS, 154, 443 • “Mid-IR spectroscopy of disks around classical T Tauri stars” • Quillen, A. C., et al., 2004, ApJL, 612, L137 • “On the planet and the disk of CoKu Tauri/4” • Varnière, P., et al., 2006, ApJL, 637, L125 • “Observational properties of protoplanetary disk gaps”

  3. INTRODUCTION • Debate • About the nature and time-scales • Recent discovery of CoKu Tau/4 • Young star containing a 10 AU hole (Forrest et al., 2004) • Link between the inner hole in the disk and the presence of planet • Outer disk is still accreting • Inner hole is left after the formation of a planet

  4. PARAMETERS • Disk viscosity (ν) : • Reynolds number (Re) : • Timescale for the inward accretion (τν) : • α : viscosity parameter • cs : sound speed • h : scale height • Ω : angular rotation rate • r : radius of orbit

  5. Wavemaker moon

  6. CLEARING THE INNER DISK • Planet in the stellar disk forms a hole • Outer disk material is prevented from the accretion • Presence of the hole • Implies that the inner disk material has time to accrete onto the star • For low α and low h • Low viscosity, so high Re : higher τν • Inner disk has no time to accrete onto the star • Should be τp < τν < τage

  7. GAP OPENING • Inner disk will begin accreting after a newly formed planet opens a gap • To open a gap... • Sufficiently massive : q > 40 Re-1 • q = Mp/ M* • Mp of CoKu Tau/4 > 0.1 Mj

  8. PLANET MIGRATION • Interaction between the planet and surrounding disk • To maintain the gap, • Balance of the torque density from spiral waves and inward torque from viscous accretion • Mp < Md : outward migration • CoKu Tau/4 : lack of significant migration

  9. CoKu Tauri/4 • Location : Taurus-Auriga cloud • Spectral Type : M1.5 / Mass : 0.5 M⊙ • Luminosity : 0.6 L ⊙/Distance : 140 pc • Very special young star • Gap with radius 10 AU • Inner wall with half-height 2 AU • Gas planet with age < 1 Myr • Suggests that the planet formation can take place quite early in the evolution of protostellar systems

  10. SPECTRUM • Excess of emission • 5-8 μm : characteristic of accretion disks around young stars • Beyond 8 μm : emission from small silicate grains

  11. FM Tau vs. CoKu Tau 4 • FM Tau • Has accretion disk • Actively accreting • CoKu Tau 4 • Decrease in emission in short-wave IR • Dusty disk with a gap at 10 AU

  12. HOW THE GAP CAN EXIT • Interactions with the outer disk • Lindblad Resonances → Angular momentum • Constraints on the mass • Angular momentum → inward migration • MP > M disk edge → no migration • MP ≤ M disk edge → migration

  13. DISK MORPHOLOGY • Lindblad resonances

  14. DISK MORPHOLOGY • Proximity of the planet to the disk edge • More than one resonance • Multiple spiral density waves can be driven at these resonances • Spiral pattern depends on • Scale height and disk temperature (i.e. Smaller height and cooler disk : tightly wound) • High Reynolds number or large planet mass • Disk edge would be far from the planet

  15. INNER HOLES IN DISKS • Observation • Detected through the study of SEDs • Confirmed by direct images (scattered light image) • CO line emission in T Tauri stars • Simulation • Combination of 2D hydrodynamics simulation and 3D Monte Carlo radiative transfer code

  16. SCATTERED LIGHT IMAGE The top panels : log of the disk surface brightness viewed at an inclination of i = 5 The bottom panels : disks viewed at i = 70 On the left : no gap in the disk On the right : a gap created by a 2MJ planet at 1 AU

  17. SURFACE BRIGHTNESS PROFILE • Comparison between the two disks • * : no planet + : 2Mj planet at 1AU • Decrease near the planet and bright bump at the outer edge of the gap

  18. SPECTRAL ENERGY DISTRIBUTION • Current instruments • Insufficient spatial resolution • only detect gaps in the outer regions • SEDs • Indirect detection of planetary gaps • BUT, no unique features

  19. SEDs • IR SEDs • Left : small-hole (r=0.07 AU) • Right : large-hole (r=1 AU) • Top : ISM dust • Bottom : HH 30 dust (high portion of big grains) • Solid line : with a gap • Dotted line : no gap

  20. http://www.spitzer.caltech.edu/Media/releases/ssc2004-08/ssc2004-08v3.shtmlhttp://www.spitzer.caltech.edu/Media/releases/ssc2004-08/ssc2004-08v3.shtml

  21. SUMMARY • Recent discovery by Forrest et al.(2004) • Young stellar system with a planet (CoKu Tau 4) • Inner disk has accreted within a time equivalent to the age of the star(1 Myr) • Planet could be accreting material and interact with the disk by driving waves into the disk from resonances • Simulation of the inner hole in the disk • Direct back illumination by stellar photons of the vertical disk wall • Back illumination heats the outer gap wall (emission excess and deficit in SED)

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