The Truth about Star Formation Alyssa A. Goodman Harvard-Smithsonian Center for Astrophysics cfa-

The Truth about Star Formation We have a pretty good idea, but not a clear picture of how stars like the Sun form. (Today’s “truth”) How well we understand the formation of massive stars depends on who you ask. Is the radiation pressure limit surmountable? Mergers & Aquisitions Are there accretion disks involved at all? Has a bipolar flow really been seen from a massive star?

Molecular or Dark Clouds "Cores" and Outflows Star Formation 101 Jets and Disks Extrasolar System 1 pc

The Whole Truth

Quests for Truth, 2002 How do processes in each stage impact upon each other? (Sequential star formation, outflows reshaping clouds…) How long do “stages” 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”?

Tools for Truth Optical imaging (e.g. HST) –Extinction, reddening  dust grain sizes, dust column density distribution –Shocked gas (e.g. HH jets) Near-infrared imaging (e.g. SIRTF) –Same as optical, plus reveals deeply “embedded” young sources Thermal dust imaging (e.g. JCMT/SCUBA) –Cold dust “glows” at far-IR and sub-mm wavelengths  dust grain sizes, dust temperature Molecular spectral-line mapping (e.g. FCRAO)spectral-line mapping –Gives gas density, temperature & velocity distrbution MHD Simulations

Intensity "Velocity" Observed Spectrum Telescope  Spectrometer All thanks to Doppler Velocity from Spectroscopy

Radio Spectral-line Observations of Interstellar Clouds

Alves, Lada & Lada 1999 Radio Spectral-Line Survey Radio Spectral-line Observations of Interstellar Clouds

Velocity as a "Fourth" Dimension No loss of information Loss of 1 dimension

Un(coordinated) Molecular- Probe Line, Extinction and Thermal Emission Observations Molecular Line Map Nagahama et al CO (1-0) Survey Lombardi & Alves 2001Johnstone et al. 2001

The Best Coordinated Effort: B68 C 18 O Dust Emission Optical 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 C 18 O 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

Molecular or Dark Clouds "Cores" and Outflows Star Formation 101 Jets and Disks Extrasolar System 1 pc

Quests for Truth, 2002 How do processes in each stage impact upon each other? (Sequential star formation, outflows reshaping clouds…) How long do “stages” 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”?

Truth?: Part 1

Part II

Star Formation >>101 Bate, Bonnell & Bromm 2002 MHD turbulence gives “t=0” conditions; Jeans mass=1 M sun 50 M sun, 0.38 pc, n avg =3 x 10 5 ptcls/cc forms ~50 objects T=10 K SPH, no B or  movie=1.4 free-fall times

Molecular or Dark Clouds "Cores" and Outflows Star Formation 101 Jets and Disks Extrasolar System 1 pc

(Synthesizing) the right “starting” condition Stone, Gammie & Ostriker 1999 Driven Turbulence; M  K; no gravity Colors: log density Computational volume: Dark blue lines: B-field Red : isosurface of passive contaminant after saturation  =0.01  =1  T /10 K  n H 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 Evaluating Synthesized 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 Falloff of Correlation with Scale Magnitude of Spectral Correlation at 1 pc Padoan, Goodman & Juvela 2002 “Reality” Scaled “Superalfvenic” Models “Stochastic” Models

Molecular or Dark Clouds "Cores" and Outflows Star Formation 101 Jets and Disks Extrasolar System 1 pc

Cores: Islands of Calm in a Turbulent Sea? "Rolling Waves" by KanO Tsunenobu © The Idemitsu Museum of Arts.

Islands of Calm in a Turbulent Sea Goodman, Barranco, Wilner & Heyer 1998

Islands (a.k.a. Dense Cores) Berkeley Astrophysical Fluid Dynamics Group Barranco & Goodman 1998 AMR Simulation Simulated NH 3 Map

Goodman, Barranco, Wilner & Heyer 1998 Observed ‘Starting’ Cores: 0.1 pc Islands of (Relative) Calm  v [km s ] T A [K] TMC-1C, OH 1667 MHz  v=(0.67±0.02)T A -0.6±  v intrinsic [km s ] T A [K] TMC-1C, NH 3 (1, 1)  v intrinsic =(0.25±0.02)T A -0.10±0.05 “Coherent Core”“Dark Cloud” Size Scale Velocity Dispersion

Cores = Order from Chaos Order; N~R 0.9 ~0.1 pc (in Taurus) Chaos; N~R 0.1

Molecular or Dark Clouds "Cores" and Outflows Star Formation 101 Jets and Disks Extrasolar System 1 pc

“Giant” Outflows See references in H. Arce’s Thesis 2001

Does fecundity = demise? Bipolar outflows from young stars Stellar Winds from older stars Large Explosions (SNe, GRBs) All have the power both to create & destroy

The action of multiple outflows in NGC 1333? SCUBA 850 mm Image shows N dust (Sandell & Knee 2001) Dotted lines show CO outflow orientations (Knee & Sandell 2000)

Action of Stellar Winds

Great Bubble in Perseus

Complications Observing Biases Temporal Behavior Regional Variations

Perseus in (Warmish) Dust

Perseus in (Coldish) Molecular Gas

Temporal Evolution Mass [M sun ] Velocity [km s -1 ] Power-law Slope of Sum = -2.7 (arbitrarily >2) Slope of Each Outburst = -2 as in Matzner & McKee 2000 Example 1: Episodicity changes Energy/Momentum Deposition (time) Example 2: (Some) Young stars may zoom through ISM

1. Episodic Outflows: Steep Mass-Velocity Slopes Result from Summed Bursts Power-law Slope of Sum = -2.7 (arbitrarily >2) Slope of Each Outburst = -2 as 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

moving PV Ceph Episodic ejections from a precessing or wobbling moving source Goodman & Arce 2002

PV Ceph is moving at ~10 km s -1 Goodman & Arce 2002

“Plasmon” Model of PV Ceph Initial jet 250 km s - 1 ; star motion 10 km s -1 Goodman & Arce 2002

“Plasmon” Model of PV Ceph Goodman & Arce 2002

Complications Observing Biases Temporal Behavior Regional Variations

“Regional Variations?” Molecular Line Map Nagahama et al CO (1-0) Survey Lombardi & Alves 2001Johnstone et al. 2001

Truth?: Part 1

Part II

COMPLETE sampling as a path to missing truths 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) Mark Heyer (UMASS/FCRAO) Doug Johnstone (HIA, Canada) Scott Schnee (CfA, PhD student) Mario Tafalla (OAS, Spain) Tom Wilson (MPIfR/SMTO)

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 ~5 degrees mapped with ~5' resolution SCUBA Observations: dust column density maps, finds all "cold" source ~20" resolution on all A V >2” FCRAO/SEQUOIA 13 CO and 13 CO Observations: gas temperature, density and velocity information ~40" resolution on all A V >1 Science: –Combined Thermal Emission data: dust spectral-energy distributions, giving emissivity, T dust and N dust –Extinction/Thermal Emission inter-comparison: unprecedented constraints on dust properties and cloud distances, in addition to high-dynamic range N dust map –Spectral-line/N dust 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

COMPLE TE, 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 N 2 H + 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 N 2 H + map with CS spectra superimposed. (Lee, Myers & Tafalla 2001). 10 pc to 0.01 pc

Is this Really Possible Now? 1 day for a 13 CO map then 1 minute for a 13 CO map now

COMPLETE Preview: Discovery of a Heated Dust Ring in Ophiuchus Goodman, Li & Schnee pc

…and the famous “1RXS J ” is right in the Middle !? 2 pc

The “COMPLETE” Truth about Star Formation, c Statistical Evaluation of Outflows’ Role Evaluation of Constructive/Destructive Role of Explosions/Winds Tracking down progeny (includes USNO-B work)

Extra Slides

COMPLETE: JCMT/SCUBA >10 mag A V Perseus Ophiuchus 10 pc Johnstone, Goodman & the COMPLETE team, SCUBA 2003(?!) ~100 hours at SCUBA

L1448 Bachiller et al B5 Yu Billawala & Bally 1999 Lada & Fich 1996 Bachiller, Tafalla & Cernicharo 1994 Position-Velocity Diagrams show YSO Outflows are Highly Episodic

Outflow Episodes:Position-Velocity Diagrams Figure from Arce & Goodman 200az1a 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? Mass/Velocity Velocity

How much gas will be pulled along for the ride? Goodman & Arce 2002

Just how fast is PV Ceph going?