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Making Stars

• Alyssa A. Goodman
• Harvard-Smithsonian Center for Astrophysics

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The Need to Make Stars
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Quick Easy Stardom

1. Find a whole lot of gas
2. Add gravity
3. Wait about 1 million years for slow gravitational
   collapse
4. Turn on fusion
5. Voilà, youre a (proto)star

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Quick Easy Stardom

• 1. Find a whole lot of gas (a.k.a. a molecular
  cloud)

2. Add gravity
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Quick Easy Stardom
5. Voilà, a protostar
3. Wait about 1 million years
4. Turn on fusion
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The Hard Road to Hollywood
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The Hard Road to Hollywood

1. Find (more than) a whole lot of gas dust, break
   it into many pieces stir it up all the time
2. Add gravity, magnetic fields plenty of harsh
   light
3. Wait about 1 million years for (slow?)
   gravitational collapse While this happens, a
   disk outflow will form, thanks to the spin the
   stirring gave your creationOh, and watch out for
   other stars blobs whizzing by, trying to mess
   up your plans
4. Turn on fusion (of deuterium, and worry about
   hydrogen later)
5. Voila, youre a new star, with a spinning disk of
   hanger-on groupies that can form planets
6. Start Fusing hydrogen join the main sequence
   (Actors Equity)

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Visualization courtesy American Museum of Natural
History, Hayden Planetarium
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VARIETY
Making Stars Where? When? How?
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COMPLETE
The COordinated Molecular Probe Line
Extinction Thermal Emission Survey

• Alyssa A. Goodman, Principal Investigator (CfA)
• João Alves (ESO, Germany)
• Héctor Arce (Caltech)
• Paola Caselli (Arcetri, Italy)
• James DiFrancesco (HIA, Canada)
• Jonathan Foster (CfA, PhD Student)
• Mark Heyer (UMASS/FCRAO)
• Helen Kirk (HIA, Canada)
• Di Li (CfA)
• Doug Johnstone (HIA, Canada)
• Naomi Ridge (CfA)
• Scott Schnee (CfA, PhD student)
• Mario Tafalla (OAN, Spain)
• Tom Wilson (ESO, Germany)

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Which Stars are Made Where, When, and How?
?
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VARIETY
Making Stars Where?
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Where Lingo
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How do we know where?

• Direct Imaging (optical, near-infrared)
• Dark Nebulae and Bright Nebulae
• Extinction mapping of clouds/cores/disks
• Scattered light from disk/jet systems
• Thermal Emission from Dust (mid far-infrared,
  sub-mm)
• DarkBright!
• Reveals Temperature
• Spectral-Line Mapping (radio)
• Reveals gas motion (temperature composition)

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How do we know where?

• Direct Imaging (optical, near-infrared)
• Dark Nebulae and Bright Nebulae
• Extinction mapping of clouds/cores/disks
• Scattered light from disk/jet systems

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Dark Bright Nebulae Stars of the Silver Screen
Image E.E. Barnard, Yerkes Observatory, c. 1907
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Glossary

• Extinction--the degree of blackness on the sky
  caused by dust between background objects and an
  observer
• Emission--production of photons by some physical
  process
• Scattering--changing the direction of photons
• Absorption--removal of photons by some physical
  process
• Spectral line--emission or absorption over a very
  narrow wavelength range, caused by a change in
  the quantum mechanical state of a particular atom
  or molecule
• IRAS--Infrared Astronomy Satellite (1983)
• HST--Hubble Space Telescope (1990-)
• SST--Spitzer Space Telescope (2003-, née SIRTF)
• COMPLETE Survey--COordinated Molecular Probe Line
  Extinction Thermal Emission Survey
• More infocfa-www.harvard.edu/agoodman

Spectral line
Intensity
"Velocity"
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Quick Tutorial Absorption, Scattering Emission
Absorber
Absorption
Scatterer
Scattering
Emitter
Emission
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Extinction Absorption Scattering
Any photon that would have otherwise reached you
but doesnt is extinguished.
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Bright Dark Nebulae
Image E.E. Barnard, Yerkes Observatory, c. 1907
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Disk Silouhettes(Extinction)
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Edge-On Silouhettes
Scattered Light from Hidden Central Star
Extinction by Edge-on Disk
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To see past all the wanna-be star material, we
need a trick.
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The Trick to Seeing through the Darkness
Observe at a Wavelength LARGER than the Typical
Dust Grain!
lt0.1 micron, a.k.a. Optical BAD
Dust on Your Coffee Table (10 million million
atoms)
gt0.1 micron, a.k.a. (Near) Infrared GOOD
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Optical
Near-Infrared
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Taurus Dark Clouds
Next slide shows near-IR 1000x zoom on blobs
like these
E.E. Barnard, 5.5 hour exposure at Yerkes
Observatory, 1907 Jan. 9
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Hubble Space Telescope Near-IR Images of
Disks/Jets(c. 1998)
DG Tau B
Haro 6-5B
IRAS 043022247
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Spitzer Sees in the Dark
HH 46-47 flow poking out of a globule, optical
(DSS)
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Where?
Direct Imaging (optical, near-infrared) Dark
Nebulae and Bright Nebulae Extinction mapping
of clouds/cores/disks Scattered light from
disk/jet systems

• Thermal Emission from Dust (mid far-infrared,
  sub-mm)
• DarkBright!
• Measures Temperature
• Spectral-Line Mapping (radio)
• Reveals gas motion

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Quick ReviewAbsorption, Scattering Emission
Absorber
Absorption
Scatterer
Scattering
Emitter
Emission
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Thermal Emission
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Barnards Taurus
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Barnards Taurus
Color shows far-IR Dust Emission from IRAS
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VARIETY

• When? How? Why?

These are harder astrophysical questions We
need to know How the material is moving
(velocitydistance/time) How long configurations
last (statistics!) The distribution of stars
formed (as a function of environment time)
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Measuring Motions Molecular Line Maps
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Radio Spectral-line Observations of Interstellar
Clouds
Radio Spectral-Line Survey
Alves, Lada Lada 1999
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Velocity from Spectroscopy
Observed Spectrum
Telescope ? Spectrometer
1.5
1.0
Intensity
0.5
0.0
-0.5
All thanks to Doppler
400
350
300
250
200
150
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"Velocity"
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Velocity from Spectroscopy
Observed Spectrum
Telescope ? Spectrometer
1.5
1.0
Intensity
0.5
0.0
-0.5
All thanks to Doppler
400
350
300
250
200
150
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"Velocity"
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Spectral-Line Mapping Watching Taurus Move
Mizuno et al. 1995 13CO(1-0) integrated intensity
map from Nagoya 4-m Young star positions courtesy
L. Hartmann
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The Uncoordination Problem
Johnstone et al. 2001
Nagahama et al. 1998 13CO (1-0) Survey
Lombardi Alves 2001
Johnstone et al. 2001
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The Value of COMPLETE Observations B68
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
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• Are measuring
• How the material is moving (velocitydistance/time
  )
• How long configurations last (statistics!)
• The distribution of stars formed (as a function
  of environment time)

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Is this how Stars are Made?

• MHD turbulence gives t0 conditions Jeans
  mass1 Msun
• 50 Msun, 0.38 pc, navg3 x 105 ptcls/cc
• forms 50 objects
• T10 K
• SPH, no B or L, G
• movie1.4 free-fall times

Bate, Bonnell Bromm 2002
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Making Stars

• Alyssa A. Goodman
• Harvard-Smithsonian Center for Astrophysics

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COMPLETE PerseusIRAS FCRAO(73,000 13CO
Spectra)
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Dust Density Temperature in Perseus(on cloud
complex scale)
Dust Temperature (25 to 45 K) (Based on 60/100
microns)
Total Dust Column (0 to 15 mag AV) (Based on
60/100 microns)
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Hot Source in a Warm Shell
Column Density
Temperature


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Wavelength
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Multiwavelength Milky Way
O
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ProtoplanetaryDisk seen in Scattered Light
Triumph of Adaptive Optics
MBM 12 A

• Jayawardhana et al. 2002

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Orion Constellation Movie