Oscillating Starless Cores: The Nonlinear Regime

Abstract

In a previous paper, we modeled the oscillations of a thermally-supported (Bonnor-Ebert) sphere as non-radial, linear perturbations following a standard analysis developed for stellar pulsations. The predicted column density variations and molecular spectral line profiles are similar to those observed in the Bok globule B68 suggesting that the motions in some starless cores may be oscillating perturbations on a thermally supported equilibrium structure. However, the linear analysis is unable to address several questions, among them the stability, and lifetime of the perturbations. In this paper we simulate the oscillations using a three-dimensional numerical hydrodynamic code. We find that the oscillations are damped predominantly by non-linear mode-coupling, and the damping time scale is typically many oscillation periods, corresponding to a few million years, and persisting over the inferred lifetime of gobules.

7 pages, 7 figures, accepted by ApJ

References in corpus (9)

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• Dichotomy in the Dynamical Status of Massive Cores in Orion
• The Inevitable Future of the Starless Core Barnard 68
• Molecular Line Profiles from Contracting Dense Cores
• Starless Cloud Core L1517B in Envelope Expansion with Core Collapse
• The Evolution of Cloud Cores and the Formation of Stars
• Distortion of Magnetic Fields in Barnard 335
• A Search for Small-Scale Clumpiness in Dense Cores of Molecular Clouds
• The dense ring in the Coalsack: the merging of two subsonic flows