Accepted for publication as a chapter in Protostars and Planets VI, University of Arizona Press (2014), eds. H. Beuther, R. Klessen, C. Dullemond, Th. Henning
http://arxiv.org/abs/1312.3223

For a PDF version of the article, click here.

FORMATION OF MOLECULAR CLOUDS AND GLOBAL CONDITIONS FOR STAR FORMATION

Clare L. Dobbs
University of Exeter

Mark R. Krumholz
University of California, Santa Cruz

Javier Ballesteros-Paredes
Universidad Nacional Autónoma de México

Alberto D. Bolatto
University of Maryland, College Park

Yasuo Fukui
Nagoya University

Mark Heyer
University of Massachusetts

Mordecai-Mark Mac Low
American Museum of Natural History

Eve C. Ostriker
Princeton University

Enrique Vázquez-Semadeni
Universidad Nacional Autónoma de México


Abstract: Giant molecular clouds (GMCs) are the primary reservoirs of cold, star-forming molecular gas in the Milky Way and similar galaxies, and thus any understanding of star formation must encompass a model for GMC formation, evolution, and destruction. These models are necessarily constrained by measurements of interstellar molecular and atomic gas, and the emergent, newborn stars. Both observations and theory have undergone great advances in recent years, the latter driven largely by improved numerical simulations, and the former by the advent of large-scale surveys with new telescopes and instruments. This chapter offers a thorough review of the current state of the field.


Table of Contents

INTRODUCTION

OBSERVED PROPERTIES OF GMCs
GMCs and Star Formation
GMCs as a Component of the Interstellar Medium
Statistical Properties of GMCs
Dimensionless Numbers: Virial Parameter and Mass to Flux Ratio
GMC Lifetimes
Star Formation Rates and Efficiencies
GMCs in Varying Galactic Environments

GMC FORMATION
Localized Converging Flows
Spiral-Arm Induced Collisions
Gravitational Instability
Magneto-Jeans Instability
Parker Instability
Conversion of H to H2, and C+ to CO

STRUCTURE, EVOLUTION, AND DESTRUCTION
GMC Internal Structure
Origin of Nonthermal Motions
Mass Loss and Disruption

REGULATION OF STAR FORMATION IN GMCs
Regulation Mechanisms
Connection Between Local and Global Scales

LOOKING FORWARD
Observations
Simulations and theory

REFERENCES

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