A new method for probing magnetic field strengths from striations in the interstellar medium

Abstract

Recent studies of the diffuse parts of molecular clouds have revealed the presence of parallel, ordered low-density filaments termed striations. Flows along magnetic field lines, Kelvin-Helmholtz instabilities and hydromagnetic waves are amongst the various formation mechanisms proposed. Through a synergy of observational, numerical and theoretical analysis, previous studies singled out the hydromagnetic waves model as the only one that can account for the observed properties of striations. Based on the predictions of that model, we develop here a method for measuring the temporal evolution of striations through a combination of molecular and dust continuum observations. Our method allows us to not only probe temporal variations in molecular clouds but also estimate the strength of both the ordered and fluctuating components of the magnetic field projected on the plane-of-the-sky. We benchmark our new method against chemical and radiative transfer effects through two-dimensional magnetohydrodynamic simulations coupled with non-equilibrium chemical modelling and non-local thermodynamic equilibrium line radiative transfer. We find good agreement between theoretical predictions, simulations and observations of striations in the Taurus molecular cloud. We find a value of $27\pm 7\mu \mathrm{G}$ for the plane-of-sky magnetic field, in agreement with previous estimates via the Davis-Chandrasekhar-Fermi method, and a ratio of fluctuating to ordered component of the magnetic field of $\sim$ 10\%.

arXiv comment12 pages, 14 figures, Accepted for publication in MNRAS

References in corpus (36)

• Theory of Star Formation
• The Herschel-SPIRE instrument and its in-flight performance
• Control of star formation by supersonic turbulence
• The UMIST database for astrochemistry 2012
• The Star Formation Rate of Turbulent Magnetized Clouds: Comparing Theory, Simulations, and Observations
• Herschel view of the Taurus B211/3 filament and striations: Evidence of filamentary growth?
• The Universality of Turbulence in Galactic Molecular Clouds
• Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping
• Compressible Sub-Alfvenic MHD turbulence in Low-beta Plasmas
• Dispersion of Magnetic Fields in Molecular Clouds. I
• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• On the universality of interstellar filaments: theory meets simulations and observations
• A Large Catalog of Accurate Distances to Molecular Clouds from PS1 Photometry
• Herschel-SPIRE observations of the Polaris flare : structure of the diffuse interstellar medium at the sub-parsec scale
• A Solution Accurate, Efficient and Stable Unsplit Staggered Mesh Scheme for Three Dimensional Magnetohydrodynamics
• The Magnetic Field in Taurus Probed by Infrared Polarization
• Magnetic field amplification in turbulent astrophysical plasmas
• Changes Of Dust Opacity With Density in the Orion A Molecular Cloud
• Magnetically Aligned Velocity Anisotropy in the Taurus Molecular Cloud
• The Five College Radio Astronomy Observatory CO Mapping Survey of the Taurus Molecular Cloud
• Velocity Gradients as a Tracer for Magnetic Fields
• Ambipolar-Diffusion Timescale, Star-Formation Timescale, and the Ages of Molecular Clouds: Is There a Discrepancy?
• Intermittency of interstellar turbulence: extreme velocity-shears and CO emission on milliparsec scale
• Turbulent Gas Flows in the Rosette and G216-2.5 Molecular Clouds: Assessing Turbulent Fragmentation Descriptions of Star Formation
• Herschel's view of the large-scale structure in the Chamaeleon dark clouds
• Matching dust emission structures and magnetic field in high-latitude cloud L1642: comparing Herschel and Planck maps
• The Star Formation Rate of Molecular Clouds
• The magnetic field and dust filaments in the Polaris Flare
• Trans-Alfvenic Motions in the Taurus Molecular Cloud
• Striations in the Taurus molecular cloud: Kelvin-Helmholtz instability or MHD waves?
• Striations in molecular clouds: Streamers or MHD waves?
• SPIRE Point Source Photometry
• Essential Magnetohydrodynamics for Astrophysics
• Polarization of seven MBM clouds at high galactic latitude
• Chemistry as a diagnostic of prestellar core geometry
• Python Radiative Transfer Emission code (PyRaTE): non-LTE spectral lines simulations

Cited by in corpus (11)

• Magnetic Properties of Star-Forming Dense Cores
• Magnetic field fluctuations in anisotropic, supersonic turbulence
• Filaments and striations: anisotropies in observed, supersonic, highly-magnetised turbulent clouds
• A multi-shock model for the density variance of anisotropic, highly-magnetised, supersonic turbulence
• Probing the cold magnetized Universe with SPICA-POL (B-BOP)
• A Unified Model for the Fan Region and the North Polar Spur: A bundle of filaments in the Local Galaxy
• The density distribution and physical origins of intermittency in supersonic, highly magnetised turbulence with diverse modes of driving
• Nature of Striation in 21 cm Channel Maps: Velocity Caustics
• Magnetic field tomography in two clouds towards Ursa Major using HI fibers
• CO emission and CO hotspots in diffuse molecular gas
• The physical and the geometrical properties of simulated cold HI structures