Transcript Order from Chaos: Star Formation in a Dynamic Interstellar

Order from Chaos:
Star Formation in a Dynamic
Interstellar Medium
Alyssa A. Goodman
Harvard-Smithsonian Center for Astrophysics
WIYN Image: T.A. Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)
Order
Chaos
WIYN Image: T.A. Rector, B. Wolpa and G. Jacoby (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)
“Order”
"Cores" and
Outflows
1 pc
Molecular or
Dark Clouds
Jets and
Disks
Extrasolar System
Chaos
Magnetohydrodynamic
Waves
Outflows
Inward
Motions
MHD
Turbulence
H II Regions
Thermal
Motions
SNe/GRB
Order in a Sea of Chaos
"Rolling Waves" by KanO
Tsunenobu © The Idemitsu
Museum of Arts.
Evidence for Order in a Sea of Chaos
“Dark Cloud”
“Coherent Core”
TMC-1C, OH 1667 MHz
TMC-1C, NH 3 (1, 1)
-0.10±0.05
D v intrinsic =(0.25±0.02)T
1
9
8
8
7
7
-1
]
9
D v intrinsic [km s
-1
[km s ]
Velocity DvDispersion
1
A
6
5
4
5
4
3
3
Dv=(0.67±0.02)T
2
6
-0.6±0.1
A
2
3
4
5
6
7
8
9
2
6
7
1
TA [K]
Goodman, Barranco, Wilner & Heyer 1998
8
9
2
3
0.1
Size Scale
4
5
6
7
8
9
1
TA [K]
Evidence for Order in a Sea of Chaos
Chaos
Order
TMC-1C, OH 1667 MHz
TMC-1C, NH 3 (1, 1)
-0.10±0.05
D v intrinsic =(0.25±0.02)T
1
9
8
8
7
7
-1
]
9
D v intrinsic [km s
-1
[km s ]
Velocity DvDispersion
1
A
6
5
4
5
4
3
3
Dv=(0.67±0.02)T
2
6
-0.6±0.1
A
2
3
4
5
6
7
8
9
2
6
7
1
TA [K]
Goodman, Barranco, Wilner & Heyer 1998
8
9
2
3
0.1
Size Scale
4
5
6
7
8
9
1
TA [K]
Order in a Sea of Chaos
"Rolling Waves" by KanO
Tsunenobu © The Idemitsu
Museum of Arts.
Ancient Historical Record (c. 1993)
~0.1 pc
(in Taurus)
Order; N~R0.9
Chaos; N~R0.1
Modern
Chaos
Simulation is a
preview of work by
Bate, Bonnell &
Bromm…stay tuned
Order & Chaos
What Causes Order?
What Causes Chaos?
Order
Causes
IOTW: What sets the scale for the “Transition to Coherence?”
Probably ~ inner scale of magnetized turbulence (often ~0.1 pc)
see Larson 1995; Goodman et al. 1998; Goodman, Caselli et al. 2002
Effects
On Cores: Mass, angular velocity, shape, ionization fraction
On Stars: Multiplicity
This is not the topic for today…
Chaos
Quantifying Properties
(briefly)
Origins
(role of outflows)
How much does it matter?
(question for the future)
Nagahama et al. 1998 13CO (1-0) Survey
Molecular Line
Map
Mapping Chaos
Dust EmissionN, Tdust
ExtinctionN, dust sizes
Molecular Linesn, Tgas, N, v, sv, xi
2MASS/NICER Extinction Map of Orion
1:50
50
1 pc
55
2:00
2:00
05
10
10
20
15
1 pc
20
30
25
SCUBA
30
40
5:41:00
20
40
R.A. (2000)
40
42:00
SCUBA
42:00
Johnstone et al. 2001
Lombardi & Alves 2001
30
41:00
R.A. (2000)
30
Johnstone et al. 2001
5:40:00
Quantifying the Properties of
Chaos
“The Spectral Correlation Function and other ‘sharp’
tools can be used to compare real and simulated
spectral line data cubes.”
Simulations can map these tools’ product onto physics.
MHD Simulations as an Interpretive Tool
b=0.01
Stone, Gammie & Ostriker 1999
[T / 10 K]
b=[
2
-3
nH / 100 cm ][ B / 1.4 mG]
2
b=1
•Driven Turbulence; M K; no gravity
•Colors: log density
•Computational volume: 2563
•Dark blue lines: B-field
•Red : isosurface of passive contaminant after saturation
Spectral Line
Maps
Simulated map, based on work of Padoan, Nordlund, Juvela, et al.
Excerpt from realization used in Padoan & Goodman 2002.
Falloff of Correlation with Scale
Comparison of Real & Simulated Spectral-Line Maps
“Equipartition”
Models
“Reality”
“Stochastic”
Models
Scaled
“Superalfvenic”
Models
Magnitude of Spectral Correlation at 1 pc
Padoan &
Goodman 2002
Comparison of Real & Simulated Spectral-Line Maps
Results so far show:
– Driven turbulence gives a approximation to real ISM (see
Padoan & Goodman 2002).
Still for the future: “Customized” simulation-to-reality
comparisons
e.g. Do the number of outflows observed in a region effect
the observed Mach number there, and does a simulation
with that Mach number match that observed cloud well?
Do the details of the forcing matter? What happens if
detailed outflow simulations are included in more global
simulations? Is the “reality match” improved in any way?
The Chaos that is Outflows
1. YSO outflows are highly episodic.
2. Much momentum and energy is deposited in the
cloud (~1044 to 1045 erg, comparable or greater
than cloud K.E.)--capable of maintaining some
degree of chaos.
3. Some cloud features are all outflow.
4. Powering source of (some) outflows may move
rapidly through ISM.
See collected thesis papers of H. Arce.
(Arce & Goodman 2001a,b,c,d; Goodman & Arce 2002).
Intensity
Outflow
Maps
Velocity
Redshifted lobe
Intensity
Blueshifted lobe
Velocity
“Typical”(?!) Outflows
See references in H. Arce’s Thesis 2001
B5
Yu Billawala & Bally 1999
Bachiller et al. 1990
L1448
Lada & Fich 1996
Bachiller, Tafalla & Cernicharo 1994
“1. YSO Outflows are
Highly Episodic”
NGC2264
Figure from Arce & Goodman 2001
Outflow Episodes
HH300
Numerical
Simulation of
Steady Jet
PV diagrams for the shell material at three inclinations cut along the outflow axis for the steady jet
simulation; i is the inclination of the outflow to the plane of the sky. Solid lines are calculated using the mean
velocity of the shell material. Dashed lines are calculated using the velocity of the newly swept-up material.
Dotted lines indicate the zero velocity. (Lee, Stone, Ostiker & Mundy 2001)
A Good Guess about Episodicity
e.g. HH300
Episodicity on Many Scales
Plus “axis
wandering”!
Arce & Goodman 2001b
Reipurth et al. 2000
Mass-Velocity Relations can be
very steep, especially in “burstylooking” sources…
Yu, Billawala, Bally, 1999
B5
“Steep” M-v
Relations
-3
• Slope steepens when t
corrections made
-8
– Previously unaccounted-for
mass at low velocities
• Slope often (much) steeper
than -2
• Seems burstier sources
have steeper slopes?
HH300 (Arce & Goodman 2001a)
-4
-8
Numerical
Simulation
of BowShock Jet
MV relationships at three inclinations for
the steady jet simulation. Both the
redshifted (open squares) and blueshifted
(filled squares) masses are shown. The
dashed lines are the fits to the redshifted
mass with a power-law MV relationship,
where the power-law index, , is indicated
at the upper right-hand corner in each
panel. The solid line at i = 0° is calculated
from the ballistic bow shock model.
Mass-Velocity Relations in Episodic Outflows: Steep
Slopes result from Summed Bursts
10
0
Power-law Slope of Sum = -2.7
(arbitrarily >2)
Mass [Msun]
10
10
10
10
10
Slope of Each Outburst = -2
-1
as in Matzner & McKee 2000
-2
-3
-4
-5
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0.1
3
4 5 6 78
2
3
1
4
5 6 78
2
10
Velocity [km s-1]
Arce & Goodman 2001b
“2. Much momentum and energy is deposited in the cloud
(~1044 to 1045 erg, comparable or greater than cloud K.E.).”
BUT: Is there a “typical” amount?
H. Arce’s Thesis 2001
“3. Some cloud features are all outflow.
That’s how much gas is shoved around!”
Arce & Goodman 2001b; 2002a
“4. Powering source of (some) outflows may
move rapidly through ISM.”
PV Ceph:
Episodic
ejections from
precessing or
wobbling
moving source
Implied source motion ~10 km/s
(4 mas/year)
assuming jet velocity ~100 km/s
Goodman & Arce 2002
“4. Powering
source of (some)
outflows may
move rapidly
through ISM.”
Goodman & Arce 2002
HST WFPC2 Overlay: Padgett et al. 2002
Goodman & Arce 2002
Arce & Goodman 2002
Trail & Jet
Goodman & Arce 2002
4x10
Trails of Deception
18
500x10
70
15
3
60
Star
Distance along x-direction (cm)
y knot positions (cm)
2
Star-Knot
Difference
(%)
50
300
Star-Knot
Difference
40
30
200
1
20
Knot
100
s-1;
Initial jet 250 km
star motion 10 km s-1
10
0
0
0
-4x 10
17
-2
5
10
15x10
0
x k not pos ns . w.r.t. s tar "now" (c m)
Elapsed Time since Burst (Years)
3
0
Knot Offset/Star Offset (Percent)
400
How Many
Outflows are
There at Once?
What is their
cumulative
effect?
How Many
Outflows are
There at Once?
What is their
cumulative
effect?
Action of Outflows(?) in NGC 1333
•SCUBA 850 mm Image shows Ndust
(Sandell & Knee 2001)
•Dotted lines show CO outflow
orientations (Knee & Sandell 2000)
Chaos
Quantifying Properties
SCF
Origins
Role of Outflows
How much does it matter?
The COMPLETE Survey
The
SIRTF
Legacy
Survey
SIRTF’s
1st Plan for
Star-Forming
Regions
“From Molecular Cores to Planet-Forming Disks”
Neal J. Evans, II, Principal Investigator (U. Texas)
Lori E. Allen (CfA)
Geoffrey A. Blake (Caltech)
Paul M. Harvey (U. Texas)
David W. Koerner (U. Pennsylvania)
Lee G. Mundy (Maryland)
Philip C. Myers (CfA)
Deborah L. Padgett (SIRTF Science Center)
Anneila I. Sargent (Caltech)
Karl Stapelfeldt (JPL)
Ewine F. van Dishoeck (Leiden)
SIRTF Legacy Survey
Perseus Molecular Cloud Complex
(one of 5 similar regions to be fully
mapped in far-IR by SIRTF Legacy)
SIRTF Legacy Survey
MIRAC Coverage
2 degrees ~ 10 pc
The
COordinated
Molecular
Probe
Line
Extinction
Thermal
Emission
Survey
Our Plan for the
Future:
COMPLETE
Alyssa A. Goodman, Principal Investigator (CfA)
João Alves (ESA, Germany)
Héctor Arce (Caltech)
Paola Caselli (Arcetri, Italy)
James DiFrancesco (Berkeley)
Doug Johnstone (HIA, Canada)
Scott Schnee (CfA)
Mario Tafalla (OAS, Spain)
Tom Wilson (MPIfR/SMTO)
Nagahama et al. 1998 13CO (1-0) Survey
Un(coordinated)
Molecular-Probe
Line, Extinction and
Thermal Emission
Observations
Molecular Line
Map
2MASS/NICER Extinction Map of Orion
1:50
50
1 pc
55
2:00
2:00
05
10
10
20
15
1 pc
20
30
25
SCUBA
30
40
5:41:00
20
40
R.A. (2000)
40
42:00
SCUBA
42:00
Johnstone et al. 2001
Lombardi & Alves 2001
30
41:00
R.A. (2000)
30
Johnstone et al. 2001
5:40:00
The Value of Coordination
Optical
Image
Dust Emission
C18O
Coordinated Molecular-Probe Line, Extinction &
Thermal Emission Observations of Barnard 68
This figure highlights the work of Senior Collaborator
João Alves and his collaborators. The top left panel
shows a deep VLT image (Alves, Lada & Lada 2001).
The middle top panel shows the 850 mm continuum
emission (Visser, Richer & Chandler 2001) from the dust
causing the extinction seen optically. The top right panel
highlights the extreme depletion seen at high extinctions
in C18O emission (Lada et al. 2001). The inset on the
bottom right panel shows the extinction map derived from
applying the NICER method applied to NTT near-infrared
observations of the most extinguished portion of B68.
The graph in the bottom right panel shows the incredible
radial-density profile derived from the NICER extinction
map (Alves, Lada & Lada 2001). Notice that the fit to
this profile shows the inner portion of B68 to be
essentially a perfect critical Bonner-Ebert sphere
NICER
Extinction
Map
Radial Density
Profile, with Critical
Bonnor-Ebert
Sphere Fit
Is this Really Possible Now?
10
A V~5 mag, Resolution~1'
3
1 day for a
map then
A V~30 mag, Resolution~10"
13CO
10
Time (hours)
10
10
13
CO Spectra for 32 Positions
in a Dark Cloud (S/N~3)
Sub-mm Map of a Dense Core
at 450 and 850
mm
2
1 Week
1 Day
1
0
1 Hour
NICER/8-m
10
-1
1 Minute
SEQUOIA+
10
10
-2
1 minute for a
13CO map now
SCUBA-2
-3
1 Second
10
NICER/2MASS
-4
1980
1985
1990
1995
NICER/SIRTF
2000
Year
2005
2010
2015
5 degrees (~tens of
pc)
COMPLETE, Part 1
Observations:
SIRTF Legacy
Coverage of
Perseus
Mid- and Far-IR SIRTF Legacy Observations: dust temperature and column density maps
~5 degrees mapped with ~15" resolution (at 70 mm)
NICER/2MASS Extinction Mapping: dust column density maps, used as target list in HHT
& FCRAO observations + reddening information ~5 degrees mapped with ~5' resolution
HHT Observations: dust column density maps, finds all "cold" source ~20" resolution on all
AV>2”
FCRAO/SEQUOIA 13CO and 13CO Observations: gas temperature, density and velocity
information ~40" resolution on all AV>1
Science:
Combined Thermal Emission (SIRTF/HHT) data: dust spectral-energy distributions, giving
emissivity, Tdust and Ndust
Extinction/Thermal Emission inter-comparison: unprecedented constraints on dust
properties and cloud distances, in addition to high-dynamic range Ndust map
Spectral-line/Ndust Comparisons Systematic censes of inflow, outflow & turbulent
motions will be enabled—for regions with independent constraints on their density.
CO maps in conjunction with SIRTF point sources will comprise YSO outflow census
(Lee, Myers & Tafalla 2001).
COMPLETE,
Part 2
FCRAO N2H+ map with CS spectra superimposed.
Observations, using target list generated from Part 1:
NICER/8-m/IR camera Observations: best density profiles for dust
associated with "cores". ~10" resolution
SCUBA Observations: density and temperature profiles for dust
associated with "cores" ~10" resolution
FCRAO+ IRAM N2H+ Observations: gas temperature, density and
velocity information for "cores” ~15" resolution
Science:
Multiplicity/fragmentation studies
Detailed modeling of pressure structure on <0.3 pc scales
Searches for the "loss" of turbulent energy (coherence)
Order from Chaos:
Star Formation in a Dynamic
Interstellar Medium
Alyssa A. Goodman
Harvard-Smithsonian Center for Astrophysics
WIYN Image: T.A. Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)
Chaos