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L6 - Stellar Evolution I: November-December, 2006 1rene@astro.su.se
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 2rene@astro.su.se
L 6: Circumstellar Disks
Background image: HH 30 JHK HST-NICMOS, courtesy Padgett et al. 1999, AJ 117, 1490
The Formation of StarsChapters: 11, 13
L6 - Stellar Evolution I: November-December, 2006 3rene@astro.su.se
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: 549Zuckerman & Song, ARAA 2004, 42: 685
Protostars & Planets V (2005)
L6 - Stellar Evolution I: November-December, 2006 4rene@astro.su.se
L 6: Circumstellar Disksand Outflows
L6 - Stellar Evolution I: November-December, 2006 5rene@astro.su.se
Flattened structures - Disks
Inevitable consequence of star formation
Rotation Magnetic Fields
3
5
2
114
2
1
cen
collapseShu assumes Eq.(10.50)
yr10s10K10AU3.0
the:Palla&Stahler
tT
l radiuscentrifuga
Rotation
L6 - Stellar Evolution I: November-December, 2006 6rene@astro.su.se
Flattened structures - Disks
Inevitable consequence of star formation
Rotation
P.S. Laplace 1796, 1799
Exposition du systeme du mondeMechanique celeste
I. Kant 1755
Allgemeine Naturgeschichte und Theorie des Himmels
Planetary System Formation
Astrobiology School: Q1+2 2007
L6 - Stellar Evolution I: November-December, 2006 7rene@astro.su.se
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 8rene@astro.su.se
Lynden-Bell & Pringle 1974, MNRAS 168, 603:
Keplerian Disk
Differential Rotation + Viscosity
Mass Transport InwardsAngular Momentum Transport Outwards
L6 - Stellar Evolution I: November-December, 2006 9rene@astro.su.se
`standard model´: e.g., Frank, King & Raine Accretion Power in Astrophysicsself-consistent structure of steady, optically thick -disk
blackbody radiation and thin disk approximation
turbturbturb
s
2
1
2
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3
4c
H
cc
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v 1, :Sunyaev & Shakura
onprescripti viscosity .8
onconservati momentumangular and mass 13
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relationopacity .6
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mequilibriu chydrostati vertical /
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l
Hc
R
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-, qpqTp
R
R
R
MGMσT
Tc
kTP
Pc
RGM
cH
H
When / Where valid ?
L6 - Stellar Evolution I: November-December, 2006 10rene@astro.su.se
Example:
Lin & Papaloizou opacities(1985 PP II):
Icy grains
H-
Moleculesbound-freefree-free(Cox-Stuart-Alexander)
L6 - Stellar Evolution I: November-December, 2006 11rene@astro.su.se
Beckwith et al. 2000, PP IV
Grain Opacities
See Ph. Thebault’s lecture
L6 - Stellar Evolution I: November-December, 2006 12rene@astro.su.se
`standard model´: e.g., Frank, King & Raine Accretion Power in Astrophysicsself-consistent structure of steady, optically thick a-disk
Te
kTh
dRR
D
i
c
hF
R
M
R
R
R
RRR
RMM,
TPρ, Σ, H, c
kTh
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form thehas
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from foundist then city drift velo radial The
...,,,parameter any and
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in
L6 - Stellar Evolution I: November-December, 2006 13rene@astro.su.se
40 observed SEDs of T Tauri Stars & `mean model´ of star+disk
D´Alessio et al. 1999
HABE Disk Structure:
Dullemond & Dominik 2004
includes vertical
Temperaturedistribution
L6 - Stellar Evolution I: November-December, 2006 14rene@astro.su.se
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 , T, …, XYZ, ..., ,..., ...)
Models Adams & Shu 1986 (flat)[examples] Kenyon & Hartmann 1987 (flared)
Malbet & Bertout 1991 (vertical structure)D´Allessio et al. 1998,... 2003Aikawa & Herbst 1998 (chemistry)Nomura 2002 (2D)Wolf 2003 (3D) See G. Mellema’s lecture
L6 - Stellar Evolution I: November-December, 2006 15rene@astro.su.se
Observations of Keplerian Disks
JE Keeler 1895ApJ 1: 416
The Rings of Saturnspectrum
image
Courtesy Brandeker, Liseau & Ilyn 2002
L6 - Stellar Evolution I: November-December, 2006 16rene@astro.su.se
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 17rene@astro.su.se
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 18rene@astro.su.se
Gas Disks - Sizes
Size scale (AU) Tracer (mode)* Reference 20000 CS (1- 0) (S) Kaifu et al. 19845000 - 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
Fridlund et al. 2002for
One Object: L1551
Size depends on frequency/mode of observation*S=single dish, I=Interferometer
L6 - Stellar Evolution I: November-December, 2006 19rene@astro.su.se
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
generally
L6 - Stellar Evolution I: November-December, 2006 20rene@astro.su.se
Gas Disks - Masses
H2
GasDirectly
COandDust
blueshifted CO
redshifted CO
continuum
L6 - Stellar Evolution I: November-December, 2006 21rene@astro.su.se
Gas Disks - Masses
Lower limit: 0.001 to 1 MSun (based on mm / submm continuum)
How good are these numbers ?
Do we understand disks ?
? Why ?
dust
gas+dust
Solar Minimum Mass Nebula = 0.002 MSun
L6 - Stellar Evolution I: November-December, 2006 22rene@astro.su.se
Gas Disks - Make up
gas disks consist of gas and dust
what components?
what proportions?
L6 - Stellar Evolution I: November-December, 2006 23rene@astro.su.se
2 T Tauri Disks - Make up
van Zadelhoff 2002
13CO (1)*
HCO+ (5)
HCN (5)
CO (200)
HCO+ (200)
HCN (200)
LkCa 15 TW Hya*(N) = depletion factor
L6 - Stellar Evolution I: November-December, 2006 24rene@astro.su.se
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 25rene@astro.su.se
Gas Disks - Evolution
Time scales (viscous accretion disk)
tdyn ~ ttherm ~ (H/R)2 tvisc
tdyn ~ 1/Kepler
~ 10-3 - 10-2
H/R << 1
if T ~ R-1/2 , tvisc ~ R
tvisc ~ 105 yr (/0.01)-1 (R/10 AU)
L6 - Stellar Evolution I: November-December, 2006 26rene@astro.su.se
Gas Disks - Evolution
Disk dispersal and disk lifetimes
Physical MechanismsHollenbach et al. 2000 PPIV
SE = Stellar Encounter (tidal stripping) WS = Stellar wind stripping evap E = photoevaporation external starevap c = photoevaporation central star
All for Trapezium conditions
T ~ R-0.5 , tvisc ~ R tvisc ~ 105 yr (/0.01)-1 (R/10 AU)
L6 - Stellar Evolution I: November-December, 2006 27rene@astro.su.se
Gas (T Tauri) Disks - Evolution
Disk dispersal and disk lifetimes
Mass accretion evolutionCalvet et al. 2000 PPIV
Average Error Bar
L6 - Stellar Evolution I: November-December, 2006 28rene@astro.su.se
Gas Disks to Debris Disks – Evolution ?
See also lecture by Ph. Thebault
fdust = LIR/L vs stellar age
(F)IR - excess
Stellar luminosity(bolometric)
How ?
L6 - Stellar Evolution I: November-December, 2006 29rene@astro.su.se
Gas Disks to Debris Disks – Evolution ?
Spangler et al. 2001
ClustersIndividual stars
(= 1 zodi)
L6 - Stellar Evolution I: November-December, 2006 30rene@astro.su.se
HR
479
6A
Pic
HD
213
62
Rieke et al. 2005, ApJ 620, 1010
24 m Spitzer data266 ms stars
2
1
t
t
L6 - Stellar Evolution I: November-December, 2006 31rene@astro.su.se
Debris Disks - Properties
debris (collision products) or particulate (gas free)
percentage of Main Sequence stars (15%?)(observationally) biased towards Spectral Type Afor (detectable) ages <400 Myr Habing et al. 1999, 2001
disk sizes 100 to 2000 AUdisk 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 32rene@astro.su.se
http://www.hep.upenn.edu/~davidk/bpic.html
L6 - Stellar Evolution I: November-December, 2006 33rene@astro.su.se
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 34rene@astro.su.se
Putting it all together
OutflowsInfallDisks
L 1551 IRS 5 - a protostellar binary
L6 - Stellar Evolution I: November-December, 2006 35rene@astro.su.se
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 36rene@astro.su.se
2 Jets !!! – HST-R + spectroscopy
Fridlund & Liseau 1998, ApJ 499, L75
N: Bright and Fast
S: Faint and Slow
L6 - Stellar Evolution I: November-December, 2006 37rene@astro.su.se
Also 2 Radio Jets – 3.5 cm VLA (arcsec)
Rodriguez et al. 2003, ApJ 586, L137
Counter jet(s)
L6 - Stellar Evolution I: November-December, 2006 38rene@astro.su.se
Proper Motion of Disk Sources - VLA 2cmRodriguez et al. 2003, ApJ 583, 330
S,DN,D
o,D
o,D,
2 where
,1.0 massesDisk
2.1 0.1
:system 5 IRS theof mass Dynamical
mm
Mm
Mmm
ii
ii
ii
L6 - Stellar Evolution I: November-December, 2006 39rene@astro.su.se
curves)( burning deuteriummax and 153.0
4
res temperatueffective and esluminositi Surface
Do0
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o
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4
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Stahler et al. - Stahler - Palla & Stahler1980 through 1993
F. Palla, priv. communication
Mass-Radius relation
(M/R)
L6 - Stellar Evolution I: November-December, 2006 40rene@astro.su.se
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 41rene@astro.su.se
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 42rene@astro.su.se
adapted from Liseau, Fridlund & Larsson 2005, ApJ, 619, 959
MHD x-wind models: ang. momentum parameter J
L6 - Stellar Evolution I: November-December, 2006 43rene@astro.su.se
L6 - Stellar Evolution I: November-December, 2006 44rene@astro.su.se
Stellar Atmosphere ModelsObserved Spectrum (upper curves)Combined Rotating Model (lower )
L6 - Stellar Evolution I: November-December, 2006 45rene@astro.su.se
After collaps and /or main accretion phase:
Pre-main-sequence evolution begins...
... next lecture by G. Gahm
L6 - Stellar Evolution I: November-December, 2006 46rene@astro.su.se
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 ?
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