Order from Chaos:Star Formation in a Dynamic Interstellar Medium

Alyssa A. GoodmanHarvard-Smithsonian Center for Astrophysics

WIYN Image: T.A. Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)

Order

WIYN Image: T.A. Rector, B. Wolpa and G. Jacoby (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)

Chaos

Molecular or Dark Clouds

"Cores" and Outflows

“Order”

Jets and Disks

Extrasolar System

1 p

c

Outflows

MagnetohydrodynamicWaves

Thermal Motions

MHDTurbulence

InwardMotions

SNe/GRBH II Regions

Chaos

Order in a Sea of Chaos

"Rolling Waves" by KanO Tsunenobu © The Idemitsu Museum of Arts.

Evidence for Order in a Sea of Chaos

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TMC-1C, OH 1667 MHz

v=(0.67±0.02)TA-0.6±0.1

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TMC-1C, NH3 (1, 1)

vintrinsic=(0.25±0.02)T A-0.10±0.05

Goodman, Barranco, Wilner & Heyer 1998

“Coherent Core”“Dark Cloud”

Size Scale

Velo

city

Dis

pers

ion

Evidence for Order in a Sea of Chaos

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TMC-1C, OH 1667 MHz

v=(0.67±0.02)TA-0.6±0.1

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TMC-1C, NH3 (1, 1)

vintrinsic=(0.25±0.02)T A-0.10±0.05

Goodman, Barranco, Wilner & Heyer 1998

OrderChaos

Size Scale

Velo

city

Dis

pers

ion

Order in a Sea of Chaos

"Rolling Waves" by KanO Tsunenobu © The Idemitsu Museum of Arts.

Ancient Historical Record (c. 1993)

Order; N~R0.9

~0.1 pc(in Taurus)

Chaos; N~R0.1

ModernChaos

Simulation is a preview of work by

Bate, Bonnell & Bromm…stay

tuned

Order & Chaos

What Causes Order?

What Causes Chaos?

Order

CausesIOTW: 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 fractionOn 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)

2MASS/NICER Extinction Map of Orion

Mapping ChaosDust EmissionN, Tdust

ExtinctionN, dust sizes

Molecular Linesn, Tgas, N, v, v, xi

5:41:0040 20 40 42:00

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1 pc

SCUBA

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1 pc

SCUBA

Molecular Line Map

Nagahama et al. 1998 13CO (1-0) Survey

Lombardi & Alves 2001Johnstone et al. 2001 Johnstone et al. 2001

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

Stone, Gammie & Ostriker 1999•Driven Turbulence; M K; no gravity•Colors: log density•Computational volume: 2563

•Dark blue lines: B-field•Red : isosurface of passive contaminant after saturation

=0.01 =1

T / 10 K

nH 2 / 100 cm-3 B / 1.4 G 2

Simulated map, based on work of Padoan, Nordlund, Juvela, et al.

Excerpt from realization used in Padoan & Goodman 2002.

Spectral Line Maps

Comparison of Real & Simulated Spectral-Line Maps

Fallo

ff o

f C

orr

ela

tion

wit

h S

cale

Magnitude of Spectral Correlation at 1 pc

Padoan & Goodman 2002

“Reality”

Scaled “Superalfvenic”Models

“Stochastic”Models

“Equipartition”Models

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 comparisonse.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).

Redshifted lobeBlueshifted

lobe

Velocity

Inte

nsi

ty

Velocity

Inte

nsi

ty

Outflow Maps

“Typical”(?!) Outflows

See references in H. Arce’s Thesis 2001

L1448

Bach

iller

et

al. 1

990

B5

Yu B

illaw

ala

& B

ally

199

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Lada &

Fic

h 1

99

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Bach

iller,

Tafa

lla &

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icharo

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“1. YSO Outflows are Highly Episodic”

Outflow Episodes

Figure

fro

m A

rce &

Goodm

an 2

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HH300

NGC2264

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

Arce & Goodman 2001b

Reipurth et al. 2000

Episodicity on Many Scales

Plus “axis wandering”!

B5Yu, Billawala, Bally, 1999

Mass-Velocity Relations can bevery steep, especially in “bursty-looking” sources…

“Steep” M-v Relations

HH300 (Arce & Goodman 2001a)

• Slope steepens when corrections made– Previously unaccounted-

for mass at low velocities

• Slope often (much) steeper than -2

• Seems burstier sources have steeper slopes?

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Numerical

Simulation of Bow-Shock 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.

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Mass

[M

sun]

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Velocity [km s-1]

Mass-Velocity Relations in Episodic Outflows: Steep Slopes result from Summed Bursts

Power-law Slope of Sum = -2.7(arbitrarily >2)

Slope of Each Outburst = -2as in Matzner & McKee 2000

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

Goodman & Arce 2002

HST WFPC2 Overlay: Padgett et al. 2002

Arce & Goodman 2002

Goodman & Arce 2002

Trail & Jet

Trails of Deception4x1018

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y knot positions (cm)

-4x1017

-2 0

x knot posns. w.r.t. star "now" (cm)

500x1015

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Distance along x-direction (cm)

15x103

1050

Elapsed Time since Burst (Years)

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Knot Offset/Star Offset (Percent)

Knot

Star

Star-KnotDifference

Star-KnotDifference

(%)

Initial jet 250 km s-1; star motion 10 km s-1

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 m Image shows Ndust (Sandell & Knee 2001)•Dotted lines show CO outflow orientations (Knee & Sandell 2000)

Chaos

Quantifying PropertiesSCF

OriginsRole of Outflows

How much does it matter?The COMPLETE Survey

SIRTF’s1st Plan for

Star-FormingRegions

The SIRTFLegacySurvey

“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

Our Plan for theFuture:

COMPLETE

The COordinated Molecular Probe Line Extinction Thermal Emission Survey

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)

2MASS/NICER Extinction Map of Orion

Un(coordinated) Molecular-Probe Line, Extinction

and Thermal Emission

Observations

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Molecular Line Map

Nagahama et al. 1998 13CO (1-0) Survey

Lombardi & Alves 2001Johnstone et al. 2001 Johnstone et al. 2001

The Value of CoordinationC18ODust EmissionOptical

Image

NICER Extinction Map

Radial Density Profile, with Critical

Bonnor-Ebert Sphere Fit

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 m 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

Is this Really Possible Now?

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Time (hours)

20152010200520001995199019851980

Year

1 Hour

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SCUBA-2

SEQUOIA+

NICER/8-m

NICER/SIRTFNICER/2MASS

AV~5 mag, Resolution~1'

AV~30 mag, Resolution~10"

13CO Spectra for 32 Positions in a Dark Cloud (S/N~3)

Sub-mm Map of a Dense Core at 450 and 850 m

1 day for a 13CO map then

1 minute for a 13CO map now

COMPLETE, Part 1

Observations:Mid- and Far-IR SIRTF Legacy Observations: dust temperature and column density maps ~5 degrees mapped with ~15" resolution (at 70 m)

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

5 degrees (~tens of pc)

SIRTF Legacy Coverage of Perseus

COMPLETE, Part 2

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" resolutionFCRAO+ 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)

FCRAO N2H+ map with CS spectra superimposed.

(Le

e,

Mye

rs &

Ta

falla

20

01

).

Order from Chaos:Star Formation in a Dynamic Interstellar Medium

Alyssa A. GoodmanHarvard-Smithsonian Center for Astrophysics

WIYN Image: T.A. Rector (NOAO/AURA/NSF) and Hubble Heritage Team (STScI/AURA/NASA)

Chaos