Annu. Rev. Astron. Astrophys. 2012. 50:531-608 Copyright © 2012 by Annual Reviews. All rights reserved

Reprinted with kind permission from Annual Reviews, 4139 El Camino Way, Palo Alto, California, USA

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Abstract: We review progress over the past decade in observations of large-scale star formation, with a focus on the interface between extragalactic and Galactic studies. Methods of measuring gas contents and star formation rates are discussed, and updated prescriptions for calculating star formation rates are provided. We review relations between star formation and gas on scales ranging from entire galaxies to individual molecular clouds.

Keywords: star formation, galaxies, Milky Way

Table of Contents

• OVERVIEW
• Introduction
• Definitions and Conventions
• Questions
• ISM DIAGNOSTICS: GAS AND DUST
• ISM Basics
• Clouds and Their Structures
• Dust as an ISM Tracer
• Gas Tracers
• The Cold Atomic Phase
• Molecular Gas
• Dense Gas Tracers
• Summary
• Mass Functions of Stars, Clusters, and Gas Structures
• SFR DIAGNOSTICS: THE IMPACT OF MULTI-WAVELENGTH OBSERVATIONS
• Star Counting and CMD Analysis
• Ultraviolet Continuum Measurements: The Impact of GALEX
• Emission-Line Tracers
• Infrared Emission: The Impact of Spitzer and Herschel
• Radio Continuum Emission
• X-ray Emission
• Composite Multi-Wavelength Tracers
• An Updated Compendium of Integrated SFR Calibrations
• The Challenge of Spatially-Resolved Star Formation Rates in Galaxies
• THE LOCAL PERSPECTIVE: FROM THE INSIDE LOOKING OUT
• Outline of low-mass star formation
• Formation of Clusters and High-mass Stars
• Theoretical Aspects
• Summary Points from the Local Perspective
• THE GALACTIC PERSPECTIVE: FROM THE OUTSIDE LOOKING IN
• The Milky Way as a Star-forming Galaxy
• Surveys
• The Milky Way as a Whole
• Radial Distributions
• Non-axisymmetric Structure
• Demographics of Star-Forming Galaxies Today
• The High-Density Regime: Starbursts
• The Low SFR and Low Density Regimes
• STAR FORMATION RELATIONS
• The Disk-Averaged Star Formation Law
• Radial Distributions of Star Formation and Gas
• The Star Formation Law on Sub-Kiloparsec Scales
• Local Measurements of Star Formation Relations
• TOWARD A SYNTHESIS
• Summary: Clues from Observations
• The Low-density Regime
• The Intermediate-density Regime
• The High-density Regime
• Clues from Studies of Molecular Clouds
• Some Speculations
• Future Prospects
• REFERENCES