Protostellar Disks: Birth, Life and Death

Neal Turner Jet Propulsion Laboratory, California Institute of Technology

Protostellar Disks: Protostellar Disks: Birth, Life and DeathBirth, Life and Death

National Aeronautics and Space Administration

The Life of Protostellar Disks

1. Jets and Winds2. Basic disk properties3. Angular momentum transport4. Evolution of the solids



Hartigan et a

l. 1995 / A

ntoniucci et al. 2008


McKee & Ostriker 2007


Pyo et al. 2005


Zinnecker et al. 1998


Takam

i et al. 2001


Burrow

s et al. 199

6


C. Lad

a 1985


Girart et al. 2006


Tam

ura et al. 1999


T. R

ay et al. 1997


Johns-Krull 2007


Ferreira et al. 2006


Spruit 1996National Aeronautics and Space Administration

Anderson et al. 2003

Size of the Launching Region?

Jet power = Rate of work done against the magnetic torque= (Footpoint orbital frequency) x (Angular momentum flux):

€

v p,∞2

2= Ω0ϖ∞vφ ,∞

Infer launching region lies 0.3 to 4 AU from the star.

Assumes energy and momentum conserved along streamlines.


Y. Kato 2004


Nakam

ura &

Li 20

07

Outflow-Driven Turbulence 1


Outflow-Driven Turbulence 2

Cloud kinetic energy vT2 dissipates on a crossing time R/vT, so

the outflows can provide the stirring if

With R=10 pc, vT=10 km s-1, f=0.01, vJ=300 km s-1 and jet mass flow rate 10-7 Solar masses per year,

the outflows are sufficient to power the turbulence.

i.e., if the outflow kinetic luminosity is greater than the dissipation rate in the gas associated with the star.

€

M•

J vJ2 >

M*vT2

f

vT

R


Basic Disk Properties


Hartmann & Kenyon 1996National Aeronautics and Space Administration

M. Simon et al. 2000


Andrews & Williams 2007National Aeronautics and Space Administration

Andrews & Williams 2007National Aeronautics and Space Administration

Origins of the Surface Density Profile

In steady-state Shakura-Sunyaev -disk,

€

Σ ~M

•

ν~

M•

Ωμ

αT~ R−1

if irradiation controls the temperature profile.


Weidenschillin

g 1977


Dullemond et al. 2007National Aeronautics and Space Administration



Bergin et al. 2007National Aeronautics and Space Administration

K. R. Bell et al. 1995National Aeronautics and Space Administration

Hartmann et al. 1993National Aeronautics and Space Administration

Angular Momentum Transport


1. Gravitational Instability1. Gravitational Instability


1. Gravitational Instability1. Gravitational Instability


Small disturbances grow if

r

H

M

r

Σ

*

2


Gam

mie 2001


Gam

mie 2001


Mejia et al. 2005

With slower cooling, instability leads to sustained accretion.


Balbus &

Haw

ley 1991

2. M

agn

eto

-Ro

tati

on

al

2. M

agn

eto

-Ro

tati

on

al

Tu

rbu

len

c eT

urb

ule

nce


Az

c

v 2B

albus & H

awley 1991

2. M

agn

eto

-Ro

tati

on

al

2. M

agn

eto

-Ro

tati

on

al

Tu

rbu

len

c eT

urb

ule

nce



Ga

mm

ie 1

99

6

Na

tion

al A

ero

na

utic

s a

nd

Sp

ace

Ad

min

istr

atio

n

Three Ways to Lose Magnetic Flux


Ionization ProcessesIonization Processes

Stellar X-Rays

Interstellar Cosmic Rays

Long-Lived Radionuclides

At 1 AU in the minimum mass

Solar nebula

Midplane ionisation is weak!

Short-Lived Radionuclides


Wardle 2007National Aeronautics and Space Administration

1

2Azv

Sa

no

& S

ton

e 2

00

2b

MRI turbulence requires


1 m Grains


No Grains


H. Li et al. 2001

P


Lodato & Clarke 2004National Aeronautics and Space Administration

Evolution of the Solids


van Boekel et al. 20

04

Na

tion

al A

ero

na

utic

s a

nd

Sp

ace

Ad

min

istr

atio

n

van Boekel et al. 20

04

Na

tion

al A

ero

na

utic

s a

nd

Sp

ace

Ad

min

istr

atio

n

TEM image of a thin-sectioned Wild 2 grain consisting of enstatite with exsolution lamellae of diopside, formed from a melt (H. Leroux)


Natta et al. 20

07

ResolvedUnresolved


Furlan et al. 200

6


Da

hm

& H

illen

bra

nd

20

07


Du

llem

on

d &

Do

min

ik 20

04

Set

tlin

g is

rap

id in

a la

min

ar d

isk

Set

tlin

g is

rap

id in

a la

min

ar d

isk


A Rough Estimate of Grain Growth Timescales

Particles settle at the terminal speed, with the force of gravity balancing the force of the gas molecules striking from below:

Particles remain compact spheres.

Particles grow by sweeping up smaller, stationary grains:

€

dz

dt= vsett =

−mg

ρcsσ

€

dm

dt=10−2 ρvsettσ


Settling Only


Settling & Sweeping


Particle growth: extreme cases

BPCA

Ballistic Particle-Cluster Agglomeration

⇓

ballistic hit-and-stick impacts of single dust particles into growing

dust agglomerate

BCCA

Ballistic Cluster-Cluster Agglomeration

⇓

ballistic hit-and-stick collisions between equal-mass dust

agglomerates

i = 1,024 i = 1,024From J. Blum


BPCAN=2

From J. Blum


BPCAN=4

From J. Blum


BPCAN=8

From J. Blum


BPCAN=16

From J. Blum


BPCAN=32

From J. Blum


BPCAN=64

From J. Blum


BPCAN=128

From J. Blum


BPCAN=256

From J. Blum


BPCAN=512

From J. Blum


BPCAN=1024

From J. Blum


BCCAN=2

From J. Blum


BCCAN=4

From J. Blum


BCCAN=8

From J. Blum


BCCAN=16

From J. Blum


BCCAN=32

From J. Blum


BCCAN=64

From J. Blum


BCCAN=128

From J. Blum


BCCAN=256

From J. Blum


BCCAN=512

From J. Blum


BCCAN=1024

From J. Blum


Radial Drift

Hot, Dense

Cold, Less

Dense


Radial Drift

Hot, Dense

Cold, Less

Dense€

vφ2 = vK

2 +R

ρ

∂P

∂R

≈ vK2 − cs

2

vφ ≈ 1−H 2

2R2

⎛

⎝ ⎜

⎞

⎠ ⎟vK


Radial Drift

Hot, Dense

Cold, Less

Dense

Grain v=vK


Weidenschilling &

Cuzzi 1993

1 AU in MMSN


Non-fractal Aggregate Growth

(Hit-and-Stick)

Cratering/Fragmentatio

n

Non-fractal Aggregate Sticking + Compaction

Cratering/Fragmen-tation/Accretion

Non

-fra

cta

l A

gg

reg

ate

S

tickin

g +

Com

pacti

on

Frac

tal A

ggre

gate

Growth

(Hit-

and-

Stick)

Restructuring/Compaction

Frag

men

tatio

n

»0

«0

EXPERI

MENTS

Bounc

ing

Non

-fra

cta

l A

gg

reg

ate

G

row

th(H

it-a

nd

-Sti

ck)

Cra

teri

ng

/Fra

gm

en

-ta

tion

/Accre

tion

Cra

teri

ng

/Fra

gm

en

tati

on

Erosion

Ero

sio

n

A

COMPILATION

Fro

m J

. B

lum


Diameter

Dia

mete

r

1 µm

100 m

100 µm

1 cm

1 m

1 µm 100 m100 µm 1 cm 1 m

Non-fractal Aggregate Growth

(Hit-and-Stick)

Erosion

Non

-fra

cta

l A

gg

reg

ate

S

tickin

g +

Com

pacti

on

Cra

teri

ng

/Fra

gm

en

-ta

tion

/Accre

tion

Cratering/Fragmentatio

n

Frac

tal A

ggre

gate

Growth

(Hit-

and-

Stick)

Restructuring/Compaction

Bounc

ing

Frag

men

tatio

n

»0

«0

Ero

sio

nN

on

-fra

cta

l A

gg

reg

ate

G

row

th(H

it-a

nd

-Sti

ck)

Non-fractal Aggregate Sticking + Compaction

Cratering/Fragmen-tation/Accretion

Cra

teri

ng

/Fra

gm

en

tati

on Mass

loss

Mass conservation

Mass gain

**

**

* for compact

targets only

Blum & Wurm 2008


Barranco 2008

Stirring by Kelvin-Helmholtz Instability


Stirring by Magneto-Rotational Turbulence

Turner et al. 2006


Sti

rrin

g b

y 2-

Str

eam

Inst

abili

ty

Johansen et al. 2007


The Life of Protostellar Disks

1. Jets and Winds2. Basic disk properties3. Angular momentum transport4. Evolution of the solids


Documents

Protostellar Disks: Birth, Life and Death