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L 6: Circumstellar Disks

L 6: Circumstellar Disks. Background image: HH 30 JHK HST-NICMOS, courtesy Padgett et al. 1999, AJ 117, 1490. L 6: Circumstellar Disks. The Formation of Stars Chapters: 11, 13. Background image: HH 30 JHK HST-NICMOS, courtesy Padgett et al. 1999, AJ 117, 1490. L 6: Circumstellar Disks.

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L 6: Circumstellar Disks

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  1. L 6: Circumstellar Disks Background image: HH 30 JHK HST-NICMOS, courtesy Padgett et al. 1999, AJ 117, 1490 L6 - Stellar Evolution I: November-December, 2006

  2. L 6: Circumstellar Disks The Formation of Stars Chapters: 11, 13 Background image: HH 30 JHK HST-NICMOS, courtesy Padgett et al. 1999, AJ 117, 1490 L6 - Stellar Evolution I: November-December, 2006

  3. L 6: Circumstellar Disks Recent reviews include: Protostars & Planets IV, Mannings, Boss & Russell (eds.) 12 Articles on Disks 5 Articles on Outflows Zuckerman, ARAA 2001, 39: 549 Zuckerman & Song, ARAA 2004, 42: 685 Protostars & Planets V (2005) L6 - Stellar Evolution I: November-December, 2006

  4. L 6: Circumstellar Disks and Outflows L6 - Stellar Evolution I: November-December, 2006

  5. Flattened structures - Disks Inevitable consequence of star formation Rotation Rotation Magnetic Fields L6 - Stellar Evolution I: November-December, 2006

  6. Flattened structures - Disks Inevitable consequence of star formation Rotation I. Kant 1755 Allgemeine Naturgeschichte und Theorie des Himmels P.S. Laplace 1796, 1799 Exposition du systeme du monde Mechanique celeste Planetary System Formation Astrobiology School: Q1+2 2007 L6 - Stellar Evolution I: November-December, 2006

  7. Mass Loss - Outflows Inevitable consequence of star formation Angular Momentum Loss - Redistribution The race between mass accretion & mass loss processses L6 - Stellar Evolution I: November-December, 2006

  8. Lynden-Bell & Pringle 1974, MNRAS 168, 603: Keplerian Disk Differential Rotation + Viscosity Mass Transport Inwards Angular Momentum Transport Outwards L6 - Stellar Evolution I: November-December, 2006

  9. `standard model´: e.g., Frank, King & Raine Accretion Power in Astrophysics self-consistent structure of steady, optically thick a-disk blackbody radiation and thin disk approximation When / Where valid ? L6 - Stellar Evolution I: November-December, 2006

  10. Example: Lin & Papaloizou opacities (1985 PP II): Icy grains H- Molecules bound-free free-free (Cox-Stuart-Alexander) L6 - Stellar Evolution I: November-December, 2006

  11. Grain Opacities See Ph. Thebault’s lecture Beckwith et al. 2000, PP IV L6 - Stellar Evolution I: November-December, 2006

  12. `standard model´: e.g., Frank, King & Raine Accretion Power in Astrophysics self-consistent structure of steady, optically thick a-disk L6 - Stellar Evolution I: November-December, 2006

  13. 40 observed SEDs of T Tauri Stars & `mean model´ of star+disk HABE Disk Structure: Dullemond & Dominik 2004 includes vertical Temperature distribution D´Alessio et al. 1999 L6 - Stellar Evolution I: November-December, 2006

  14. Gas Disks – Structure Models Steady Disks around Single Stars Boundary Conditions Rin : boundary layer, magnetosphere, hole? Rout: ad hoc? , interstellar turbulence? Viscosity MHD/rotation (Hawley & Balbus 1995) Opacity k = k(r, T, …, XYZ, ..., z0,..., cn ...) Models Adams & Shu 1986 (flat) [examples] Kenyon & Hartmann 1987 (flared) Malbet & Bertout 1991 (vertical structure) D´Allessio et al. 1998,... 2003 Aikawa & Herbst 1998 (chemistry) Nomura 2002 (2D) Wolf 2003 (3D) See G. Mellema’s lecture L6 - Stellar Evolution I: November-December, 2006

  15. Observations of Keplerian Disks JE Keeler 1895 ApJ 1: 416 The Rings of Saturn spectrum image Courtesy Brandeker, Liseau & Ilyn 2002 L6 - Stellar Evolution I: November-December, 2006

  16. 2 Categories of Disks observed T Tauri Disks: around young stars (0.1 - 10 Myr) of half a solar mass (0.1 - 1 Msun) at 150 pc distance (50 - 450 pc) in and/or near molecular clouds Accretion Disks Debris Disks: around young ms-stars (10 - 400 Myr) of about a solar mass (1 - 2 Msun) at 20 pc distance (3 - 70 pc) in the general field Vega-excess stellar disks gas rich gas poor L6 - Stellar Evolution I: November-December, 2006

  17. Frequency of Disks High Rate of occurence around young stars NGC 2024 86% Trapezium cluster 80% IC 348 65% Haisch et al. 2001 and around BDs in Trapezium cluster 65% Muench et al. 2001 see also G. Gahm’s lecture L6 - Stellar Evolution I: November-December, 2006

  18. Gas Disks - Sizes Fridlund et al. 2002 for One Object: L1551 Size scale (AU) Tracer (mode)* Reference 20000 CS (1- 0) (S) Kaifu et al. 1984 5000 - 10000 13CO (1- 0) (S) Fridlund et al. 1989 1400 C18O (1- 0) (I) Sargent et al. 1988 <500 1.4 mm (I) Woody et al. 1989 45 + 1600 mm, cm (I) Keene & Masson 1990 200 0.8 mm (I) Lay et al. 1994 7000 H13CO+ (1- 0) (S) Mizuno et al. 1994 5000 0.7 - 1 mm (S) Ladd et al. 1995 4000 - 6000 C18, 17O (2- 1) (S) Fuller et al. 1995 1200 13CO (1- 0) (I) Ohashi et al. 1996 4000 H13CO+ (1- 0) (I) Saito et al. 1996 5000 H12, 13CO+ (1- 0) (S, I) Hogerheijde et al.1997, 98 2500 C18O+ (1- 0) (I) Momose et al. 1998 10 7 mm (I) Rodriguez et al. 1998 20000 CH3OH (2-1), (5-4) (S) White et al. 2006 *S=single dish, I=Interferometer Size depends on frequency/mode of observation L6 - Stellar Evolution I: November-December, 2006

  19. generally Gas Disks - Sizes T Tauri/HABE disks 50 - 100 AU Dust: mm-continuum interferometry 100 - 300 AU Dust: scattered stellar light 300 AU Gas: CO lines (evidence for Kepler rotation) Silhouettte disks (``proplyds´´) up to 1000 AU Dust: scattered stellar light L6 - Stellar Evolution I: November-December, 2006

  20. Gas Disks - Masses continuum H2 Gas Directly CO and Dust blueshifted CO redshifted CO L6 - Stellar Evolution I: November-December, 2006

  21. Gas Disks - Masses ? Why ? Lower limit: 0.001 to 1 MSun(based on mm / submm continuum) gas+dust dust How good are these numbers ? Do we understand disks ? Solar Minimum Mass Nebula = 0.002 MSun L6 - Stellar Evolution I: November-December, 2006

  22. Gas Disks - Make up gas disks consist of gas and dust what components? what proportions? L6 - Stellar Evolution I: November-December, 2006

  23. 2 T Tauri Disks - Make up 13CO (1)* HCO+ (5) HCN (5) CO (200) HCO+ (200) HCN (200) *(N) =depletion factor van Zadelhoff 2002 LkCa 15 TW Hya L6 - Stellar Evolution I: November-December, 2006

  24. 2 T Tauri Disks - Chemistry Molecular abundances (rel. H2) Species LkCa 15 TW Hya CO 3.4 ( - 7) 5.7 ( - 8) HCO+ 5.6 (-12) 2.2 (-11) H13CO+< 2.6(-12) 3.6 (-13) DCO+ …. 7.8 (-13) CN 2.4 (-10) 1.2 (-10) HCN 3.1 (-11) 1.6 (-11) H13CN …. < 8.4(-13) HNC …. < 2.6(-12) DCN …. < 7.1(-14) CS 8.5 (-11) …. H2CO 4.1 (-11) < 7.1(-13) CH3OH < 3.7(-10)< 1.9(-11) N2H+< 2.3(-11)< 1.8(-11) H2D+< 1.5(-11)< 7.8(-12) Thi 2002 L6 - Stellar Evolution I: November-December, 2006

  25. Gas Disks - Evolution • Time scales (viscous accretion disk) • tdyn ~ attherm ~ a (H/R)2tvisc • tdyn ~ 1/WKepler • ~ 10-3 - 10-2 H/R << 1 if T ~ R-1/2 , tvisc ~R tvisc ~ 105 yr (a/0.01)-1 (R/10 AU) L6 - Stellar Evolution I: November-December, 2006

  26. Gas Disks - Evolution Disk dispersal and disk lifetimes SE = Stellar Encounter (tidal stripping) WS = Stellar wind stripping evap E = photoevaporation external star evap c = photoevaporation central star All for Trapezium conditions Physical Mechanisms Hollenbach et al. 2000 PPIV T ~ R-0.5 , tvisc ~ R tvisc ~ 105 yr (a/0.01)-1 (R/10 AU) L6 - Stellar Evolution I: November-December, 2006

  27. Gas (T Tauri) Disks - Evolution Disk dispersal and disk lifetimes Average Error Bar Mass accretion evolution Calvet et al. 2000 PPIV L6 - Stellar Evolution I: November-December, 2006

  28. Gas Disks to Debris Disks – Evolution ? How ? fdust = DLIR/Lvs stellar age See also lecture by Ph. Thebault (F)IR - excess Stellar luminosity (bolometric) L6 - Stellar Evolution I: November-December, 2006

  29. Gas Disks to Debris Disks – Evolution ? Clusters Individual stars (= 1 zodi) Spangler et al. 2001 L6 - Stellar Evolution I: November-December, 2006

  30. HR 4796A b Pic HD 21362 24 mm Spitzer data 266 ms stars Rieke et al. 2005, ApJ 620, 1010 L6 - Stellar Evolution I: November-December, 2006

  31. Debris Disks - Properties debris (collision products) or particulate (gas free) percentage of Main Sequence stars (15%?) (observationally) biased towards Spectral Type A for (detectable) ages <400 Myr Habing et al. 1999, 2001 disk sizes 100 to 2000 AU disk masses >1 to 100 MMoon(small grains) see Ph. Thebault’s lecture Pre-IRAS Solar system Zodi US Navy Chaplain G. Jones 1855 AJ 4, 94 Vega Blackwell et al. 1983 L6 - Stellar Evolution I: November-December, 2006

  32. http://www.hep.upenn.edu/~davidk/bpic.html L6 - Stellar Evolution I: November-December, 2006

  33. How much Gas in Dusty Debris Disks ? Disk evolution hypothesis: gas-rich to gas-poor Census of material (mgas/mdust): planet formation planet formation: enough gas for GPs ? planet formation: time scales? planet formation: seeds of Life ? See astrobiology lecture L6 - Stellar Evolution I: November-December, 2006

  34. Putting it all together Outflows Infall Disks L 1551 IRS 5 - a protostellar binary L6 - Stellar Evolution I: November-December, 2006

  35. L 1551 IRS 5 Jet blue 10´´ Molecular Outflow – CO blue 2 arcmin Optical Image (NTT, R-band) L6 - Stellar Evolution I: November-December, 2006

  36. N: Bright and Fast S: Faint and Slow 2 Jets !!! – HST-R + spectroscopy Fridlund & Liseau 1998, ApJ 499, L75 L6 - Stellar Evolution I: November-December, 2006

  37. Counter jet(s) Also 2 Radio Jets – 3.5 cm VLA (arcsec) Rodriguez et al. 2003, ApJ 586, L137 L6 - Stellar Evolution I: November-December, 2006

  38. Proper Motion of Disk Sources - VLA 2cm Rodriguez et al. 2003, ApJ 583, 330 L6 - Stellar Evolution I: November-December, 2006

  39. Stahler et al. - Stahler - Palla & Stahler 1980 through 1993 F. Palla, priv. communication Mass-Radius relation (M/R) L6 - Stellar Evolution I: November-December, 2006

  40. Putting it all together: observation + theory of infall + theory of mass loss L 1551 IRS 5 - a protostellar binary L6 - Stellar Evolution I: November-December, 2006

  41. Putting it all together: observation + theory of infall + theory of mass loss L 1551 IRS 5 - a protostellar binary L6 - Stellar Evolution I: November-December, 2006

  42. MHD x-wind models: ang. momentum parameter J adapted from Liseau, Fridlund & Larsson 2005, ApJ, 619, 959 L6 - Stellar Evolution I: November-December, 2006

  43. L6 - Stellar Evolution I: November-December, 2006

  44. Observed Spectrum (upper curves) Combined Rotating Model (lower ) Stellar Atmosphere Models L6 - Stellar Evolution I: November-December, 2006

  45. After collaps and /or main accretion phase: Pre-main-sequence evolution begins... ... next lecture by G. Gahm L6 - Stellar Evolution I: November-December, 2006

  46. L 6: conclusions • circumstellar disks are a consequence of star • formation • disks and bipolar outflows/jets are connected • disks form potentially planetray systems • L 6: open questions • what are the physics of disks and their outflows ? • how do disks evolve ? • what fraction forms planetary systems ? • when and how ? L6 - Stellar Evolution I: November-December, 2006

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