PhD_04

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L 6 Circumstellar Disks
Background image HH 30 JHK HST-NICMOS, courtesy
Padgett et al. 1999, AJ 117, 1490
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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
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L 6 Circumstellar Disks
Recent reviews include Protostars Planets IV,
Mannings, Boss Russell (eds.)
12 Articles
on Disks
5 Articles on Outflows Zuckerma
n, ARAA 2001, 39 549 Zuckerman
Song, ARAA 2004, 42 685 Protostars Planets V
(2005)
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L 6 Circumstellar Disks and Outflows
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Flattened structures - Disks
Inevitable consequence of star formation
Rotation
Rotation
Magnetic Fields
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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 Q12 2007
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Mass Loss - Outflows
Inevitable consequence of star formation
Angular Momentum Loss - Redistribution
The race between mass accretion mass loss
processses
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Lynden-Bell Pringle 1974, MNRAS 168, 603
Keplerian Disk Differential Rotation
Viscosity
Mass Transport Inwards Angular Momentum Transport
Outwards
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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 ?
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Example Lin Papaloizou opacities (1985 PP
II) Icy grains H- Molecules bound-free free-free
(Cox-Stuart-Alexander)
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Grain Opacities
Beckwith et al. 2000, PP IV
See Ph. Thebaults lecture
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standard model e.g., Frank, King Raine
Accretion Power in Astrophysics self-consistent
structure of steady, optically thick a-disk
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40 observed SEDs of T Tauri Stars mean
model of stardisk
HABE Disk Structure Dullemond Dominik 2004
includes vertical Temperature distribution
DAlessio et al. 1999
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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) DAllessio et al. 1998,...
2003 Aikawa Herbst 1998 (chemistry) Nomura
2002 (2D) Wolf 2003 (3D)
See G. Mellemas lecture
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Observations of Keplerian Disks
JE Keeler 1895 ApJ 1 416 The Rings of Saturn
spectrum
image
Courtesy Brandeker, Liseau Ilyn 2002
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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
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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. Gahms lecture
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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
lt500 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
Ssingle dish, IInterferometer
Size depends on frequency/mode of observation
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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
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Gas Disks - Masses
continuum
H2 Gas Directly
CO and Dust
blueshifted CO
redshifted CO
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Gas Disks - Masses
? Why ?
Lower limit 0.001 to 1 MSun (based on mm / submm
continuum)
dust
gasdust
How good are these numbers ?
Do we understand disks ?
Solar Minimum Mass Nebula 0.002 MSun
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Gas Disks - Make up
gas disks consist of gas and dust what
components? what proportions?
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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
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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 lt
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 . lt
8.4(-13) HNC . lt 2.6(-12) DCN . lt
7.1(-14) CS 8.5 (-11) . H2CO 4.1
(-11) lt 7.1(-13) CH3OH lt 3.7(-10) lt
1.9(-11) N2H lt 2.3(-11) lt 1.8(-11) H2D lt
1.5(-11) lt 7.8(-12)
Thi 2002
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Gas Disks - Evolution

• Time scales (viscous accretion disk)
• tdyn a ttherm a (H/R)2 tvisc
• tdyn 1/WKepler
• 10-3 - 10-2
• H/R ltlt 1
• if T R-1/2 , tvisc R
• tvisc 105 yr (a/0.01)-1 (R/10 AU)

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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)
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Gas (T Tauri) Disks - Evolution
Disk dispersal and disk lifetimes
Average Error Bar
Mass accretion evolution Calvet et al. 2000 PPIV
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Gas Disks to Debris Disks Evolution ?
How ?
fdust DLIR/L vs stellar age
See also lecture by Ph. Thebault
(F)IR - excess
Stellar luminosity (bolometric)
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Gas Disks to Debris Disks Evolution ?
Clusters Individual stars
( 1 zodi)
Spangler et al. 2001
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HR 4796A b Pic HD 21362
24 mm Spitzer data 266 ms stars
Rieke et al. 2005, ApJ 620, 1010
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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 lt400 Myr Habing
et al. 1999, 2001 disk sizes 100 to 2000
AU disk masses gt1 to 100 MMoon (small
grains)


see Ph. Thebaults lecture

Pre-IRAS Solar system Zodi US Navy
Chaplain G. Jones 1855 AJ 4, 94
Vega Blackwell et al. 1983
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http//www.hep.upenn.edu/davidk/bpic.html
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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
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Putting it all together Outflows Infall Disks L
1551 IRS 5 - a protostellar binary
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L 1551 IRS 5
Jet blue 10
Molecular Outflow CO blue
2 arcmin
Optical Image (NTT, R-band)
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N Bright and Fast
S Faint and Slow
2 Jets !!! HST-R spectroscopy Fridlund
Liseau 1998, ApJ 499, L75
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Counter jet(s)
Also 2 Radio Jets 3.5 cm VLA (arcsec) Rodriguez
et al. 2003, ApJ 586, L137
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Proper Motion of Disk Sources - VLA
2cm Rodriguez et al. 2003, ApJ 583, 330
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Stahler et al. - Stahler - Palla
Stahler 1980 through 1993 F. Palla, priv.
communication
Mass-Radius relation (M/R)
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Putting it all together observation theory of
infall theory of mass loss L 1551 IRS 5 - a
protostellar binary
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Putting it all together observation theory of
infall theory of mass loss L 1551 IRS 5 - a
protostellar binary
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MHD x-wind models ang. momentum parameter J
adapted from Liseau, Fridlund Larsson 2005,
ApJ, 619, 959
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(No Transcript)
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Observed Spectrum (upper curves) Combined
Rotating Model (lower )
Stellar Atmosphere Models
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After collaps and /or main accretion
phase Pre-main-sequence evolution begins...
... next lecture by G. Gahm
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• 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 ?