Oscillating Filaments: I - Oscillation and Geometrical Fragmentation

Abstract

We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid based AMR-code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, e.g. with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process `geometrical fragmentation'. In our realization the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristical scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.

7 pages, 7 figures, accepted by ApJ, supplementary info and videos available at https://www.youtube.com/channel/UCWIm4aFjenMapWlUDMPW6cA

References in corpus (9)

• Molecular Cloud Evolution II. From cloud formation to the early stages of star formation in decaying conditions
• Inefficient star formation through turbulence, magnetic fields and feedback
• The Nature of the Dense Core Population in the Pipe Nebula: Thermal Cores Under Pressure
• The Birth of Molecular Clouds: Formation of Atomic Precursors in Colliding Flows
• On the nature of star-forming filaments: I. Filament morphologies
• Chains of dense cores in the Taurus L1495/B213 complex
• Aspect Ratio Dependence of the Free-Fall Time for Non-Spherical Symmetries
• Investigating the Global Collapse of Filaments Using Smoothed Particle Hydrodynamics
• Non-linear dense core formation in the dark cloud L1517

Cited by in corpus (22)

• Filamentary Fragmentation and Accretion in High-Mass Star-Forming Molecular Clouds
• From diffuse gas to dense molecular cloud cores
• Interstellar filaments and star formation
• Probing fragmentation and velocity sub-structure in the massive NGC 6334 filament with ALMA
• Large-scale periodic velocity oscillation in the filamentary cloud G350.54+0.69
• Temperature structure and kinematics of the IRDC G035.39-00.33
• Structure and Fragmentation of a high line-mass filament: Nessie
• Fragmentation of star-forming filaments in the X-shape Nebula of the California molecular cloud
• L1495 Revisited: A PPMAP View of a Star-Forming Filament
• Analytical core mass function (CMF) from filaments: Under which circumstances can filament fragmentation reproduce the CMF?
• On the fragmentation of filaments in a molecular cloud simulation
• Magnetic tension and instabilities in the Orion A integral shaped filament
• Merging Filaments I: A race against collapse
• Characterising the high-mass star forming filament G351.776--0.527 with Herschel and APEX dust continuum and gas observations
• Dynamical Ejections of Stars due to an Accelerating Gas Filament
• Role of Filamentary Structures in the Formation of Two Dense Cores, L1544 and L694-2
• On filament fragmentation and the impact of ambient environment on it
• Fates of the dense cores formed by fragmentation of filaments: do they fragment again or not?
• Velocity-Coherent Substructure in TMC-1: Inflow and Fragmentation
• Decaying turbulence in molecular clouds: how does it affect filament networks and star formation?
• Core formation via filament fragmentation and the impact of ambient pressure on it
• Investigations of MWISP Filaments. I. Filament Identification and Analysis Algorithms, and Source Catalogue