Download Disk Structure

Disk Structure
Early objects : understanding disk formation
SED : IR to mm

Gas dynamics

Circumstellar disks
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Keplerian disks
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Dust properties, dust coagulation
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Physical structure
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Chemistry
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Debris disks
Multiwavelength observations
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The quest for planet formation
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Future opportunities
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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
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Cieza et al. 2007
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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
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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
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Early objects
PROSAC
survey
Jorgensen
et al.
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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).
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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
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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
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Radial Structure
Hughes et al. 08
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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)
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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
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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
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Dust properties
Kessek
er et al
2006
MIDI observations , spatial variation of
silicates (crystalline vs amorphous)
Van Boeckel 2004
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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)
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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 ?

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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
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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

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Gas dynamics
Envelope + Outer disk :
Brinch et al. 2007 L1489-IRS mis-alignment of disk and
envelope ?
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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.
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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.

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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

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Disk Chemistry
Qi et al. 2004, 2008; SMA
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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).
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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 ?
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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

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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
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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 ??)
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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 +
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FIRI : Far IR Interferometer
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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
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