The Evolution of Cloud Cores and the Formation of Stars

Abstract

For a number of starless cores, self-absorbed molecular line and column density observations have implied the presence of large-amplitude oscillations. We examine the consequences of these oscillations on the evolution of the cores and the interpretation of their observations. We find that the pulsation energy helps support the cores and that the dissipation of this energy can lead toward instability and star formation. In this picture, the core lifetimes are limited by the pulsation decay timescales, dominated by non-linear mode-mode coupling, and on the order of ~few x 10^5--10^6 yr. Notably, this is similar to what is required to explain the relatively low rate of conversion of cores into stars. For cores with large-amplitude oscillations, dust continuum observations may appear asymmetric or irregular. As a consequence, some of the cores that would be classified as supercritical may be dynamically stable when oscillations are taken into account. Thus, our investigation motivates a simple hydrodynamic picture, capable of reproducing many of the features of the progenitors of stars without the inclusion of additional physical processes, such as large-scale magnetic fields.

12 pages, 7 figures, submitted to ApJ

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Cited by in corpus (12)

• The dynamics of collapsing cores and star formation
• Chemistry and Radiative Transfer of Water in Cold, Dense Clouds
• Multi-line observations of CH${}_3$OH, c-C${}_3$H${}_2$ and HNCO towards L1544: Dissecting the core structure with chemical differentiation
• Correlating Infall with Deuterium Fractionation in Dense Cores
• Prestellar core modeling in the presence of a filament - The dense heart of L1689B
• Contraction Signatures Toward Dense Cores in the Perseus Molecular Cloud
• Infall/Expansion Velocities in the Low-Mass Dense Cores L492, L694-2, and L1521F: Dependence on Position and Molecular Tracer
• Mapping the H${}_2$D${}^{+}$ and N${}_2$H${}^{+}$ emission towards prestellar cores. Testing dynamical models of the collapse using gas tracers
• From Filaments to Oscillating Starless Cores
• Gas infalling motions in the envelopes of Very Low Luminosity Objects
• An analytical model for the evolution of starless cores I: The constant-mass case
• Sub-structure formation in starless cores