Physical Processes in Star Formation

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From Cloud to Cluster A Tale of Orion
Steven Stahler Eric Huff
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two influences 1 low-mass outflows
2 self-gravity
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two influences 1 low-mass outflows
2 self-gravity
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Accelerating Contraction
dissipation
shocks
as in stars
contraction
virial theorem
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Observation Clouds supported by turbulence.
Larson 1981
virial theorem
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Idealized Model

• spherical, isothermal

Jones Walker 1989

• turbulent dissipation

Mac Low 1999

• star formation

Schmidt 1959 (n1)
low mass only
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Contraction and Expansion
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Density Spike
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Velocity Profiles
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Low-Mass Stars in the ONC
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Conclusions
Clouds supported by dissipative, turbulent
pressure undergo -
- accelerating contraction
- accelerating star formation
Schmidt law reproduces ONC low-mass star
formation.
Density spike provides environment for high-mass
star formation.