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

Stars Forming in a Dynamic Interstellar Medium

Alyssa A. GoodmanHarvard-Smithsonian Center for Astrophysics

cfa-www.harvard.edu/~agoodman

Stars Forming in a Dynamic ISM

When the World Stood Still (except at the last minute)

Allowing Time to Tick, and not always start at zero– Episodic Outflows

– PV Ceph: Protostar Caught Speeding?

COMPLETE sampling as a path to the answer– Carefully-designed statistical questions– Serendipity (so far: warm dust ring around X-ray source in

Ophichus, odd velocity features in Perseus…)

Standing Still, Until the Last Minute

Global Instability (e.g. Jeans) Fragments Cloud

(hierarchically)

time~106 yearsHoyle 1953

Fragments Collapse UnderGravity into “Protostars”

time~105 years

Standing Still, Until the Last Minute

A Group of Young“Zero-Age Main Sequence”

Stars is Born

Molecular or Dark Clouds

"Cores" and Outflows

Ticking, from t=0

Jets and Disks

Extrasolar System

1 p

c

BUT…BUT…• How long does each “phase” last and how

are they mixed? (Big cloud--“Starless” Core--Outflow--Planet Formation--Clearing)

• What is the time-history of star production in a “cloud”? Are all the stars formed still “there”?

• How do processes in each phase impact upon each other? (Sequential star formation, outflows reshaping clouds…)

Stars Forming

in a Dynamic

ISM

Bate, Bonnell & Bromm 2002

•MHD turbulence gives “t=0” conditions; Jeans mass=1 Msun

•50 Msun, 0.38 pc, navg=3 x 105 ptcls/cc

•forms ~50 objects

•T=10 K

•SPH, no B or •movie=1.4 free-fall times

What is the right “starting” condition?

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.

Evaluating Simulated Spectral Line Map of MHD Simulations: The

Spectral Correlation

Function (SCF)

“Equipartition”Models

How Well can Molecular Clouds be Modeled, Today?Summary Results from SCF Analysis

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

Cores: Islands of Calm in a Turbulent Sea?

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

Goodman, Barranco, Wilner & Heyer 1998

Islands of Calm in a Turbulent Sea

Islands (a.k.a. Dense Cores)

Berkeley Astrophysical Fluid Dynamics Grouphttp://astron.berkeley.edu/~cmckee/bafd/results.html Barranco & Goodman 1998

AMR Simulation

Simulated NH3 Map

Ask about velocity

gradients later

Goodman, Barranco, Wilner & Heyer 1998

Observed ‘Starting’ Cores: 0.1 pc Islands of (Relative) Calm

2

3

4

5

6

7

8

9

1

v [

km s-1

]

3 4 5 6 7 8 91

2

TA [K]

TMC-1C, OH 1667 MHz

v=(0.67±0.02)TA-0.6±0.1

2

3

4

5

6

7

8

9

1

v

intr

insi

c[k

m s

-1]

6 7 8 90.1

2 3 4 5 6 7 8 91

TA [K]

TMC-1C, NH3 (1, 1)

vintrinsic=(0.25±0.02)T A-0.10±0.05

“Coherent Core”“Dark Cloud”

Size Scale

Velo

city

Dis

pers

ion

Order in a Sea of Chaos

Order; N~R0.9

~0.1 pc(in Taurus)

Chaos; N~R0.1

So, can we simulate ticking time?

• MHD Simulations give good approximation of dynamic ISM, on >>0.1 pc scales

• Physical scale (reality) of ~0.1 pc SPH simulations starting from a turbulent “t=0” is debatable (no B, T=const, etc.)

– Observations indicate relative calm just before stars form

Why care about time?

10-5

10-4

10-3

10-2

10-1

100

Mass

[M

sun]

0.12 3 4 5 6 7 8

12 3 4 5 6 7 8

102

Velocity [km s-1]

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

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

Example 1: Episodicity changes outflow’s Energy/Momentum

Deposition/time

Example 2: (Some) Young stars may zoom through

ISM

Example 1: Episodicity in Outflows

See references in H. Arce’s Thesis 2001

L1448

Bach

iller

et

al. 1

990

B5

Yu B

illaw

ala

& B

ally

199

9

Lada &

Fic

h 1

99

6

Bach

iller,

Tafa

lla &

Cern

icharo

19

94

Position-Velocity Diagrams

show YSO Outflows are Highly Episodic

Velocity

Posi

tion

Outflow Episodes:Position-Velocity Diagrams

Figure

fro

m A

rce &

Goodm

an 2

00

az1

a

HH300

NGC2264

“Steep” Mass-Velocity Relations

HH300 (Arce & Goodman 2001a)

• Slope steepens when corrections made– Previously unaccounted-

for mass at low velocities

• Slope often (much) steeper than “canonical” -2

• Seems burstier sources have steeper slopes?

-3

-8

-4

-8M

ass

/Velo

city

Velocity

10-5

10-4

10-3

10-2

10-1

100

Mass

[M

sun]

0.12 3 4 5 6 7 8

12 3 4 5 6 7 8

102

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

Example 2: Powering source of (some) outflows may zoom through ISM

1 pc

“Giant” Herbig-

Haro Flow from

PV Ceph

Image from Reipurth, Bally & Devine 1997

PV Ceph

Episodic ejections from a

precessing or wobbling

moving ?? moving ?? source

Goodman & Arce 2002

Goodman & Arce 2002

HST WFPC2 Overlay: Padgett et al. 2002

Arce & Goodman 2002

Optical “cones”Elongated ~N-S

Dense gas elongated

along direction of motion

Goodman & Arce 2002

Trail & Jet

How much gas will be pulled along for the ride?

Goodman & Arce 2002

Just how fast is PV

Ceph going?

Insights from a “Plasmon” Model4x1018

3

2

1

0

y knot positions (cm)

-4x1017

-2 0

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

500x1015

400

300

200

100

0

Distance along x-direction (cm)

15x103

1050

Elapsed Time since Burst (Years)

70

60

50

40

30

20

10

0

Knot Offset/Star Offset (Percent)

Knot

Star

Star-KnotDifference

Star-KnotDifference

(%)

Initial jet 250 km s-1; star motion

10 km s-1

Goodman & Arce 2002

Insights from a “Plasmon” Model4x1018

3

2

1

0

y knot positions (cm)

-4x1017

-2 0

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

1

2

3

4

5

6

7

8

9

10

"Dynamical Time"/Elapsed Time

3.0x1018

2.52.01.51.00.50.0

Distance of Knot from Source (cm)

Goodman & Arce 2002

Stars Forming in a Dynamic ISM

When the World Stood Still (except at the last minute)

Allowing Time to Tick, and not always start at zero– Episodic Outflows

– PV Ceph: Protostar Caught Speeding?

COMPLETE sampling as a path to the answer– Carefully-designed statistical questions– Serendipity (so far: warm dust ring around X-ray source in

Ophichus, odd velocity features in Perseus…)

2MASS/NICER Extinction Map of Orion

Un(coordinated) Molecular-Probe Line,

Extinction and Thermal Emission Observations

5:41:0040 20 40 42:00

2:00

55

50

05

10

15

20

25

30

R.A. (2000)

1 pc

SCUBA

5:40:003041:003042:00

2:00

1:50

10

20

30

40

R.A. (2000)

1 pc

SCUBA

Molecular Line Map

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

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

COMPLETEsampling as a path to the answer

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 (HIA, Canada)Doug Johnstone (HIA, Canada)

Scott Schnee (CfA, PhD student)Mario Tafalla (OAS, Spain)Tom Wilson (MPIfR/SMTO)

COMPLETE, Part 1

Observations:2003-- Mid- and Far-IR SIRTF Legacy Observations: dust temperature and column density maps ~5 degrees mapped with ~15" resolution (at 70 m)

2002-- NICER/2MASS Extinction Mapping: dust column density maps ~5 degrees mapped with ~5' resolution

2003-- SCUBA Observations: dust column density maps, finds all "cold" source ~20" resolution on all AV>2”

2002-- FCRAO/SEQUOIA 13CO and 13CO Observations: gas temperature, density and velocity information ~40" resolution on all AV>1

Science:– Combined Thermal Emission 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 enabled

– CO maps in conjunction with SIRTF point sources will comprise YSO outflow census

5 degrees (~tens of pc)

SIRTF Legacy Coverage of Perseus

>10-degree scale Near-IR Extinction, Molecular Line and

Dust Emission Surveys of Perseus, Ophiuchus

& Serpens

COMPLETE, Part 2

(2003-5)

Observations, using target list generated from Part 1:NICER/8-m/IR camera Observations: best density 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 scalesSearches for the "loss" of turbulent energy (coherence)

FCRAO N2H+ map with CS spectra superimposed.

(Le

e,

Mye

rs &

Ta

falla

20

01

).

<arcminute-scale core maps to get density & velocity structure all the way from >10 pc

to 0.01 pc

A statistical question for COMPLETE:

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)

Is this Really Possible Now?

10-4

10-3

10-2

10-1

100

101

102

103

Time (hours)

20152010200520001995199019851980

Year

1 Hour

1 Minute

1 Day

1 Second

1 Week

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

…yes, it’s possible

COMPLETE: JCMT/SCUBA>10 mag AV

2468

Perseus

Ophiuchus

10 pc

10 pc

Johnstone, Goodman & the COMPLETE team, SCUBA

2003(?!)

~100 hours at SCUBA

COMPLETE Preview:Discovery of a Heated Dust Ring in

Ophiuchus

Goodman, Li & Schnee 2003

2 pc

…and the famous “1RXS J162554.5-233037” is right in the Middle !?

2 pc

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

Stars Forming in a Dynamic Interstellar Medium

Alyssa A. GoodmanHarvard-Smithsonian Center for Astrophysics

cfa-www.harvard.edu/~agoodman

Core “Rotation”??

N2H+ in TMC-1C; Schnee & Goodman 2003

FWHM Gradient “Beam”

0.1

pc

Core “Rotation”??

N2H+ in TMC-1C; Schnee & Goodman 2003

Core “Rotation”??

N2H+ in TMC-1C; Schnee & Goodman 2003

Core “Rotation”??

N2H+ in TMC-1C; Schnee & Goodman 2003

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 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