Oscillations of starless cores

Abstract

If the split, asymmetric molecular spectral line profiles that are seen in many starless cores are interpreted as indicative of global collapse or expansion of the core then one possible implication is that most starless cores have short lifetimes on the order of the collapse or sound crossing time scale. An alternative interpretation of the line profiles as indicative of perturbations on an underlying equilibrium structure leads to the opposite implication, that many cores have long lifetimes. While evidence suggests that some cores are collapsing on a free-fall time scale, we show that observations of some other starless cores can be reproduced by a model of non-radial oscillations about the equilibrium configuration of a pressure-bounded, thermally-supported sphere (Bonnor-Ebert sphere). We model the oscillations as linear perturbations following a standard analysis developed for stellar pulsations and compare the column densities and molecular spectral line profiles predicted from a particular model to observations of the Bok globule B68.

submitted to the Astrophysical Journal

References in corpus (27)

• Dense Cores in Dark Clouds. XIV. N2H+(1-0) maps of dense cloud cores
• Systematic Molecular Differentiation in Starless Cores
• Molecular ions in L1544. II. The ionization degree
• Tracing the Mass during Low-Mass Star Formation. II. Modelling the Submillimeter Emission from Pre-Protostellar Cores
• N2H+ and C18O Depletion in a Cold Dark Cloud
• A Survey for Infall Motions toward Starless Cores. II. $CS(2-1)$ and $N_2{H}^{+}(1-0)$ Mapping Observations
• Molecular Evolution in Collapsing Prestellar Cores
• A Survey for Infall Motions toward Starless Cores. I. CS (2-1) and N${}_2$H${}^{+}$ (1-0) Observations
• Evolution of Chemistry and Molecular Line Profile during Protostellar Collapse
• Molecular ions in L1544. I. Kinematics
• New Protostellar Collapse Candidates: An HCO+ Survey of the Class 0 Sources
• Tracing the Mass during Low-Mass Star Formation. III. Models of the Submillimeter Dust Continuum Emission from Class 0 Protostars
• The dust temperature distribution in prestellar cores
• Molecular Excitation and Differential Gas-Phase Depletions in the IC 5146 Dark Cloud
• The Dynamical State of Barnard 68: A Thermally Supported, Pulsating Dark Cloud
• A High Resolution Study of the Slowly Contracting, Starless Core L1544
• Observations of L1521F: a highly evolved starless core
• A Survey For Infall Motions Toward Starless Cores. III. CS (3-2) and DCO+(2-1) Observations
• Radiative Transfer and Starless Cores
• Monte Carlo Radiative Transfer in Embedded Prestellar Cores
• How to Identify Pre-Protostellar Cores
• Dark cloud cores and gravitational decoupling from turbulent flows
• Line profiles of molecular ions toward the pre-stellar core LDN 1544
• Rotation of the pre-stellar core L1689B
• Oscillations in the stable starless core Barnard 68
• The kinetic temperature of Barnard 68
• Monte Carlo radiative transfer in molecular cloud cores

Cited by in corpus (38)

• Theory of Star Formation
• Cold Dark Clouds: The Initial Conditions for Star Formation
• Chemistry of Dark Clouds: Databases, Networks, and Models
• The Nature of the Dense Core Population in the Pipe Nebula: Thermal Cores Under Pressure
• Dynamics and Depletion in Thermally Supercritical Starless Cores
• The Different Structures of the Two Classes of Starless Cores
• The Virial Balance of Clumps and Cores in Molecular Clouds
• The Earliest Phases of Star formation observed with Herschel (EPoS): The dust temperature and density distributions of B68
• Line Profiles of Cores within Clusters: I. The Anatomy of a Filament
• Chemistry and Radiative Transfer of Water in Cold, Dense Clouds
• Protostar Formation in Supersonic Flows: Growth and Collapse of Spherical Cores
• Simulating star formation in Ophiuchus
• The Dynamical State fo the Starless Dense Core FeSt 1-457: A Pulsating Globule?
• The Dynamical State of the Starless Dense Core FeSt 1-457: A Pulsating Globule?
• Digging into the Interior of Hot Cores with ALMA (DIHCA). I. Dissecting the High-mass Star-Forming Core G335.579-0.292 MM1
• Molecular Emission Line Formation in Prestellar Cores
• Dichotomy in the Dynamical Status of Massive Cores in Orion
• Using Chemistry to Unveil the Kinematics of Starless Cores: Complex Radial Motions in Barnard 68
• First firm spectral classification of an early-B pre-main-sequence star: B275 in M17
• Evidence for Dynamically Important Magnetic Fields in Molecular Clouds
• Oscillating Starless Cores: The Nonlinear Regime
• Global Collapses and Expansions in Star-Forming Clouds
• Assessing molecular line diagnostics of triggered star formation using synthetic observations
• Intensity-Corrected Herschel Observations of Nearby Isolated Low-Mass Clouds
• 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 Approach to Collapse of Molecular Clouds
• Illuminating a tadpole's metamorphosis III: quantifying past and present environmental impact
• On the internal dynamics of starless cores: stability of starless cores with internal motions and collapse dynamics
• Illuminating a tadpole's metamorphosis II: observing the on-going transformation with ALMA
• An analytical model for the evolution of starless cores I: The constant-mass case
• The dense ring in the Coalsack: the merging of two subsonic flows
• Molecular Line Profiles from a Core Forming in a Turbulent Cloud
• Rebounding Cores to Build Star Cluster Multiple Populations
• Why do some cores remain starless ?