Striations in molecular clouds: streamers or MHD waves?
| Autor: | Konstantinos Tassis, Aris Tritsis |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Physics
Field line Molecular cloud FOS: Physical sciences Astronomy and Astrophysics Astrophysics - Astrophysics of Galaxies 01 natural sciences Instability Magnetic field Computational physics Classical mechanics Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science Astrophysics of Galaxies (astro-ph.GA) Physics::Space Physics 0103 physical sciences Streamlines streaklines and pathlines Magnetohydrodynamic drive Density contrast Magnetohydrodynamics 010306 general physics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) |
| Zdroj: | Monthly Notices of the Royal Astronomical Society. 462:3602-3615 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/stw1881 |
| Popis: | Dust continuum and molecular observations of the low column density parts of molecular clouds have revealed the presence of elongated structures which appear to be well aligned with the magnetic field. These so-called striations are usually assumed to be streams that flow towards or away from denser regions. We perform ideal magnetohydrodynamic (MHD) simulations adopting four models that could account for the formation of such structures. In the first two models striations are created by velocity gradients between ambient, parallel streamlines along magnetic field lines. In the third model striations are formed as a result of a Kelvin-Helmholtz instability perpendicular to field lines. Finally, in the fourth model striations are formed from the nonlinear coupling of MHD waves due to density inhomogeneities. We assess the validity of each scenario by comparing the results from our simulations with previous observational studies and results obtained from the analysis of CO (J = 1 - 0) observations from the Taurus molecular cloud. We find that the first three models cannot reproduce the density contrast and the properties of the spatial power spectrum of a perpendicular cut to the long axes of striations. We conclude that the nonlinear coupling of MHD waves is the most probable formation mechanism of striations. Comment: 15 pages, 20 figures, accepted to MNRAS |
| Databáze: | OpenAIRE |
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