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Article Contents

ABSTRACT

1.FORWARD

2.OBSERVING STAR-FORMING CLOUDS

2.1.Observational Techniques

2.1.1.The Problem of H₂

2.1.2.Observing the Dust

2.1.3.Molecular lines

2.1.4.Two-Level Atoms

2.2.Molecular Cloud Properties from Molecular Lines

2.2.1.Density Inference

2.2.2.Velocity and temperature inference

2.2.3.Mass inference

3.Physical processes in molecular clouds

3.1.Heating and cooling proceses

3.1.1.Heating by cosmic rays

3.1.2.CO cooling

3.2.Flows in Molecular Clouds

3.2.1.Equations of Motion

3.2.2.Dimensionless Numbers

3.3.The Virial Theorem

4.MOLECULAR CLOUD COLLAPSE

4.1.Stability Conditions

4.1.1.Thermal Pressure: the Bonnor-Ebert Mass

4.1.2.Magnetic Support: the Magnetic Critical Mass

4.2.Collapsing Cores

4.2.1.Spherical collapse

4.2.2.Rotation Collapse and the Angular Momentum Problem

4.2.3.Magnetized Collapse and the Magnetic Flux Problem

5.TWO PROBLEMS: THE STAR FORMATION RATE AND THE INITIAL MASS FUNCTION

5.1.The Star Formation Rate

5.1.1.The Observational Problem: Slow Star Formation

5.1.2.Potential Solutions

5.2.The Initial Mass Function

5.2.1.The Observed IMF

5.2.2.The IMF in the Gas Phase?

5.2.3.A Possible Model: Turbulent Fragmentation and Radiation-Suppressed Fragmentation

REFERENCES