Remarks on Rapid vs. Slow Star Formation

Abstract

We discuss problems with some observational estimates indicating long protostellar core lifetimes and large stellar age spreads in molecular clouds. We also point out some additional observational constraints which suggest that protostellar cores do not have long lifetimes before collapsing. For external galaxies, we argue that the widths of spiral arms does not imply a long star-formation process, since the formation of massive stars will disrupt molecular clouds, move material around, compress it in other regions which produce new star-forming clouds. Thus, it seems unavoidable that this cyclical process will result in an extended period of enhanced star formation, which does not represent the survival time of any individual molecular cloud. We argue that the rapid star formation indicated observationally is also easier to understand theoretically than the traditional scenario of slow quasi-static contraction with ambipolar diffusion.

15 pages, 2 tables. Includes one schematic figure illustrating why the star formation period cannot be a small fraction of the cloud lifetime. Accepted by Revista Mexicana de Astronomia y Astrofisica. Requieres rmaa.cls file (includded)

References in corpus (19)

• Kinetic Energy Decay Rates of Supersonic and Super-Alfvenic Turbulence in Star-Forming Clouds
• Turbulent Flow-Driven Molecular Cloud Formation: A Solution to the Post-T Tauri Problem?
• Clouds as Turbulent Density Fluctuations. Implications for pressure confinement and spectral line data interpretation
• Flows, Fragmentation, and Star Formation. I. Low-mass Stars in Taurus
• Gravitational Collapse in Turbulent Molecular Clouds. II. Magnetohydrodynamical Turbulence
• The Spectroscopically Determined Substellar Mass Function of the Orion Nebula Cluster
• Molecular Cloud Formation Behind Shock Waves
• Physical vs. Observational Properties of Clouds in Turbulent Molecular Cloud Models
• HI Narrow Self-Absorption in Dark Clouds: Correlations with Molecular Gas and Implications for Cloud Evolution and Star Formation
• Comments on Inferences of Star Formation Histories and Birthlines
• Quiescent and coherent cores from gravoturbulent fragmentation
• The Distribution of Pressures in a Supernova-Driven Interstellar Medium. I. Magnetized Medium
• Dynamic cores in hydrostatic disguise
• Analysis of Clumps in Molecular Cloud Models: Mass Spectrum, Shapes, Alignment and Rotation
• Ambipolar-Diffusion Timescale, Star-Formation Timescale, and the Ages of Molecular Clouds: Is There a Discrepancy?
• The Formation of Molecular Clouds
• On the Timescale for the Formation of Protostellar Cores in Magnetic Interstellar Clouds
• Can variability account for apparent age spreads in OB association colour-magnitude diagrams?
• Thermal Pressures in Neutral Clouds inside the Local Bubble, as Determined from C I Fine-Structure Excitations

Cited by in corpus (17)

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• Physical Properties of Giant Molecular Clouds in the Large Magellanic Cloud
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• Disruption of giant molecular clouds and formation of bound star clusters under the influence of momentum stellar feedback
• Optical Characterization of a New Young Stellar Population in the Serpens Molecular Cloud
• Chemistry in Protoplanetary Disks: the gas-phase CO/H2 ratio and the Carbon reservoir
• The Nature of the Velocity Field in Molecular Clouds. I. The Non-Magnetic Case
• Tracing the Galactic spiral structure with embedded clusters
• Tidal foces as a regulator of star formation in Taurus
• On the gravitational content of molecular clouds and their cores
• Accretion and Diffusion Timescales in Sheets and Filaments
• Molecular cloud formation in high-shear, magnetized colliding flows
• No evidence for intense, cold accretion onto YSOs from measurements of Li in T-Tauri stars
• The impact of magnetic fields on the chemical evolution of the supernova-driven ISM
• Does slow and steady win the race? Investigating feedback processes in giant molecular clouds
• Magnetic fields in Bok globules: Multi-wavelength polarimetry as tracer across large spatial scales
• Chemical chronology of the Southern Coalsack