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Disk Structure Early objects : understanding disk formation SED : IR to mm Gas dynamics Circumstellar disks 1 Keplerian disks Dust properties, dust coagulation Physical structure Chemistry Debris disks Multiwavelength observations The quest for planet formation Future opportunities 1 Evolution of disks HD100546 Planetary disks – Dynamics : macroscsopic solid bodies – Big grain in situ production (collisions) . Survival time scale << stellar age – asymmetries → gravitational perturbations HD141569 HR4796 Proto-planetary Disks – Dynamics: gas. – Sub-micronic grains. grain growths Augereau, étoiles de type A Adapté de Natta et al. 2000 β Pictoris Vega Disk Fraction 3 Cieza et al. 2007 3 from Bergin et al. (2006) t ~ 10 Myr , Mgas~ (10-3 – 1) MJup “Most of the physical and chemical processes that play a role in the ISM are needed to understand protoplanetary disks” - Non-thermal chemistry driven by X-ray and UV radiation, cosmic rays… Freeze-out of gas species building up of a complex ice-grain chemistry, “snow lines” Large gradients of n(H2) and T complex molecular excitation (from LTE to non-LTE) Disk rotation, accretion, viscosity, turbulence, magnetic fields complex MHD models At least a “2D” description is required radial and vertical disk characteristics GREAT CHALLENGE FOR NEXT DECADE TELESCOPES THE ROLE OF ANGULAR RESOLUTION: r (Jupiter) ~ 5 AU r (Saturn) ~ 10 AU r (Pluto) ~ 40 AU typical disk around a low-mass solar type (G,K) star Dimension on the sky r = 1 AU r = 10 AU r = 100 AU dist = 30 pc 0.07’’ 0.7’’ 7’’ dist = 100 pc 0.02’’ 0.2’’ 2’’ dist = 150 pc 0.01’’ 0.1’’ 1’’ dist = 500 pc … 0.04’’ 0.4’’ ESI-SPICA beam sizes 35-60 um 3.6’’ 60-110 um 6.1’’ 110-210 um 11.5’’ from Swinyard (SPIE, 2006) Disks will be spatially unresolved by ESI-SPICA Early objects Class 0/1 sources. No visible source, faint IR source. -> Most information from mm/submm wavelengths Distinct physical components. Infalling envelope (~0.05pc) + disk (~300 AU) + outflow (~ pc). How to separate these components ? Dust continumm --> Density structure Molecular lines --> Gas kinematics (infall, accretion, rotation) ? Need expertise in radiative transfer -> Needs mm/submm interferometer to reach subarcsec resolution 6 Early objects Class 0 : (Andre & Belloche) Rotating and infalling envelope + Molecular outflow No disk ? Other examples (Looney et al. 2003, Jorgensen et al. 2004) Detection of rotation, disk ? Most of the mass is in the envelope (infalling ?) Menv / Mdisk >~ 10 in these objects. On-going accretion. Infall(+ rotation) dominates the gas dynamics. With Menv ~ Mo, M disk <~ 0.1 Mo 7 Early objects PROSAC survey Jorgensen et al. 8 Early objects Class 1: Lommen, Jorgensen et al. (2008); Brinch et al. (2007), PROSAC survey Jorgensen (2007) Key : high angular resolution + submm (high sensitivity to dust continuum emission) Choose lines with high critical density (HCO+(3-2) (high sensitivity to densest regions, almost transparent to low density regions). 9 Early objects Class 1: Lommen, Jorgensen et al. (2008); Brinch et al. HCO+(3-2) : rotation ? IRS63 Menv/Mdisk ~0.2 . transition to class II ? M* = 0.37 +/- 0.13 Mo Mdisk ~ 0.1Mo Age ~ 5 x 105 yrs Elias 29 Menv/Mdisk ~6 . M* = 2.5 +/- 0.6 Mo Mdisk ~ 0.004 Mo Age ~ 5 x 105 yrs 10 Circumstellar Disks around TTauri stars Systematic studies dust continuum emission (eg Andrews and Williams, 2007) Fits of Temperature and column density structure using SED + submm images. Use power law distributions for Σ (exp. p) and T (exp q) Flat disk , 10 Parameters = (i, PA, r0,Rd,κo,β,T1,q,Σ5,p) Not enough information in the data → must fix some parameters (i, PA, r0,κo,β) and fit the others. Median T ~ 200 r(-0.62) K, Σ ~ 31 r(-0.5) gcm(-2) (r in AU) But it is likely that p is closer to 1 due to systematic errors and degeneracies in the fitting method. Rd ~ 200 AU with broad distribution 11 Radial Structure Hughes et al. 08 12 Radial Structure Most commonly used : truncated power law distributions + hydrostatic equilibrium.: For Rin < r < Rout Σ(r) = Σ0 (r/r0)-p T(r) = To (r/r0)-q H(r) = sqrt(2r3kT(r)/GM*μ) which gives n(r,z) = (Σ(r)/πH(r)) exp(-z/H(r)2 5 parameters (Rout, p, q, To , Σ0 ) for face-on disk. Hughes et al. (08) propose an alternative model based on Hartmann et al 98, with a tapered edge and the same number of parameters. Σ(r) = (c/rγ) exp(-(r/c2)2-γ) 13 Circumstellar disks Brown et al 2008, SMA Search for holes (gaps) + other structures Best mm/submm resolution ~0.3” (30AU @ 100 pc) Gaps : tentatively identified in SED with deficit of mid IR Confirmed with sub arcsec images (submm, IR/visible 14 with AO) Circumstellar disks LkHa330 (Brown et al 2008, SMA) : 40AU hole. hot gas (CO 850K) (and dust) very close to the star density reduction ~ 1000 in the gap rather steep edges Pietu et al 2006, PdBI LkCA15 50AU hole Contrast > 200 15 Dust properties Kessek er et al 2006 MIDI observations , spatial variation of silicates (crystalline vs amorphous) Van Boeckel 2004 16 Dust properties Grain growth : mm/submm SED : shallow slope for larger size grains. Mid-plane. Outer disk (Natta et al. 04,Rodmann et al. 06, Lommen et al. 07) κν = κ0 (ν/ν0)β, β ~ 1 (mm to cm size dust) IR : surface, inner disk shape of silicate features For mic sized grains : weaker, flatter and less peaked feature compared to ISM dust. Lommen et al. 07) 17 Grain processing Presence of crystalline silicates in all disks incl. Brown dwarfs. Grain size depends on star luminosity (Silicate emission at different radii in the disk)Kessler et al. 2007. Thermal annealing (needs 800 K) + radial transport . Other processes ? 18 Grain mantles Freeze-out + solid phase chemistry (Boogert et al. 2008) for a survey of low mass YSOs Composition H2O, CO2?CO, CH3OH, HCOOH, H2CO, NH3, NH4+ ? HCOO- ? OCN+ organic matter ? --> Strong pattern in IR spectra. --> Diagnostic of UV/X ray + Thermal history 19 Gas dynamics Outer disk : mm/submm interfrometer of rotation lines (CO, HCO+) Rotation curves, source masses + T profile (from CO, 13CO and C18O excitation) Inner disk High spectral resolution IR spectroscopy (line profiles). No rotation curve so far 20 Gas dynamics Envelope + Outer disk : Brinch et al. 2007 L1489-IRS mis-alignment of disk and envelope ? 21 Gas dynamics Outer disk : mm/submm interfrometer of rotation lines (CO, 13CO, HCO+) Piétu et al. 2007, PdBI LkCa 15, presence of CO (& 13CO) in the dust hole. Different structure in dust and gas. 22 Gas dynamics & thermal structure Outer disk : Rotation curves, star masses + T vertical profile (from CO, and 13CO excitation, Dartois et al. 2003) CO is more extended radially than 13CO : photodissociation ? 13CO probes cold gas close to the mid plane (10 – 15 K). HCO+ also 12CO probes intermediate heights HCO+ is as extended radially as CO. CO/13CO >> 60 (fractionation ?); 13CO/HCO+ ~ 300 – 1000, decreases with radius. 23 Disk Chemistry Qi et al. 2004, 2008; SMA TW Hya (56pc, Rd = 3.5” = 200 AU) CO, HCO+, H13CO+, DCO+, HCN, DCN DCO+/HCO+ first increases with radius then drops -> In situ gas phase D fractionation x(e) ~ 10(-7) assuming simple eq. chemistry 24 Disk Chemistry Qi et al. 2004, 2008; SMA 25 Inner Disk Chemistry Carr & Najita 2008 Spitzer CO, H2O, OH, C2H2, HCN, CO2 R ~ 1 to 2 AU, T : 400(CO2) to 900 (CO) K (disk photosphere). 26 Inner Disk Chemistry Squares = AA Tau Triangles : hot cores Circles : models (Marckwick et al. 2002) Carr & Najita 2008 Spitzer Large column densities (1016 to 1018cm-2), especially water ; vertical mixing ? 27 Debris disks (> 10 Myrs up to 200 Mys) hot dust (exozodis) detected with IR interferometry . Transient production of dust in the inner A Us , probably caused by dynamical phenomena in the planetary system (eg as t in LHB) ? Di Folco et al 2008 for τ Cet 28 Debris disks : example of Fomalhaut “Cold” dust detected at large radii (>20AU) 40 “ = 30 AU for Fomalhaut Kalas et al. 2005 Mid- IR (Spitzer) (Werner et al, 05) (Marsh et al. 2005) CSO SHARC 29 Finding planets in disks ? Indirect methods : structures in disks created by planets/companions : •Gaps, holes • warps •dynamical perturbations : deviation from Keplerian rotation Direct methods : •Transits • Direct imaging (AO, IR interferometry, radio ??) 30 Different wavelengths probe different grain size Combined effects dynamics + radiation pressure -> Spatial segregation of grains (Wyatt et al, 2006) Indirect signs of planets in debris disks beta Pictoris Simulations (Augereau et al. 2001b) Observation, HST/STIS (Heap et al., 2000) Signatures indirectes de planètes dans les disques • Optique/near IR: VLT/SPHERE, JWST puis ELT • ALMA 50 pc Sillon et milieu circumplanétaire Wolf & D’Angelo 2005 λ = 0.3 mm (900 GHz) exp. ~ 8 heures 100pc Simulateur ALMA: Pety et al., 2002 1 MJup (* 0.5 Msun) 5 MJup (* 2.5 Msun) Jupiter in a 0.05 Msun disk around a solar-mass star as seen with ALMA d=140pc Baseline: 10km λ=700µm, tint=4h (Wolf et al. 2002) Future Instruments Herschel (launch 2008/9). Limited spatial resolution ; complete coverage of FIR/submm : SEDs + spectroscopy (eg H2O, fine structure lines) ALMA : High spatial resolution. Continuum + molecular line studies -- Future Projects -SPICA : warm gas, O chemistry (OI, OH, H2O), fine structure lines : Deep study of inner disk (< 10 AU) Dust composition (Ices + silicates) Darwin : Nulling interferometry + FIRI : Far IR Interferometer 35 THE UNIQUE ROLE OF ESI-SPICA: ESI-SPICA can provide unique observations of far-IR continuum + OI, water and OH in protoplanetary disks - Oxygen-bearing species (OI, CO, H2O and OH) have a critical role for the disks´ physics, chemistry and dynamics of the warm gas. - ALMA will not be sensitive to the warm gas, will not observe water thermal lines, nor the atomic & ionic fine structure lines, and will not observe dust features. - Extinction will be a problem for the JWST in the mid-IR, Water is a primordial research topic in the star & planet formation processes: observation of thermal water lines can only be done from Far-IR space telescopes - Dust grains have ice-mantles, dominated by O-rich ices: H2O, CO2 , CH3OH … water ice is the most abundant ice mantle in the coldest regions: X(water-ice) > 10-4 water vapor can be the 3rd most abundant species in the warm gas: X(H2O) > 10-4 How is water is incorporated into the planet, asteroid & comet formation ?? THE UNIQUE ROLE OF ESI-SPICA: ESI-SPICA can provide unique observations of far-IR continuum + OI, water and OH in protoplanetary disks - Oxygen-bearing species (OI, CO, H2O and OH) have a critical role for the disks´ physics, chemistry and dynamics of the warm gas. - ALMA will not be sensitive to the warm gas, will not observe water thermal lines, nor the atomic & ionic fine structure lines, and will not observe dust features. - Extinction will be a problem for the JWST in the mid-IR, Water is a primordial research topic in the star & planet formation processes: observation of thermal water lines can only be done from Far-IR space telescopes - Dust grains have ice-mantles, dominated by O-rich ices: H2O, CO2 , CH3OH … water ice is the most abundant ice mantle in the coldest regions: X(water-ice) > 10-4 water vapor can be the 3rd most abundant species in the warm gas: X(H2O) > 10-4 How is water is incorporated into the planet, asteroid & comet formation ?? ESI-SPICA detections limits: closest SFRs! (Taurus, Lupus, Ophiuchus, Chamaleon, etc.) ORION ! Extrapolated from detailed models of disks Gorti & Hollenbach (2004) around solar-type stars THE END 39