scholarly journals On the Nature of Magnetohydrodynamic Turbulence in the Interstellar Medium

1990 ◽  
Vol 140 ◽  
pp. 153-154
Author(s):  
V.N. Fedorenko
Keyword(s):  
Cosmic Rays ◽  
Shock Waves ◽  
Interstellar Medium ◽  
Weak Shock ◽  
Mhd Waves ◽  
Mhd Turbulence ◽  
Magnetohydrodynamic Turbulence ◽  
Extended Spectrum

Various mechanisms of creation of the extended spectrum of MHD turbulence in the interstellar medium are reviewed. Within the scales 1014 cm ≲ L ≲ 1019 cm the turbulence mostly consists of the ensemble of weak shock waves. At 1012 cm ≲ L ≲ 1014 cm the principle mechanism is generation of MHD waves by cosmic rays.

scholarly journals Cosmic-Ray Injection into Shock-Waves

1981 ◽  
Vol 94 ◽  
pp. 361-362 ◽  
Author(s):  
Catherine J. Cesarsky ◽  
Jean-Pierre Bibring
Keyword(s):  
Cosmic Rays ◽  
Shock Waves ◽  
Interstellar Medium ◽  
Ionization Potential ◽  
Absorption Line ◽  
Cosmic Ray ◽  
Galactic Cosmic Rays ◽  
Reactive Elements ◽  
Refractory Elements ◽  
First Ionization Potential

When corrected for the effects of propagation in the interstellar medium (i.s.m.), the observed composition of galactic cosmic rays can give us some clues as to the origin of these particles. It is noteworthy that the main pecularities of the cosmic ray source composition (CRS), as compared to normal i.s.m. abundances, bear some resemblance to that of i.s. grains, as inferred from i.s. absorption line measurements (e.g. York 1976): (1) the refractory elements Al, Si, Mg, Ni, Fe and Ca, which in i.s. clouds are almost completely locked into grains, are present with normal abundance ratios in the CRS. (2) normalized to Si, the volatile and reactive elements C, N, O, S and Zn are underabundant in CRS by factors of 2.5 to 6; these elements are only partially depleted in the i.s.m. (3) at a given rigidity the ratios H/Si and He/Si are lower than in the i.s.m. by a factor of ~ 25; while H and He atoms are virtually absent in i.s. grains. (1) implies that cosmic rays originate in astrophysical sites where the grains have either not condensated as yet, or where they have been (at least partially) destroyed. Then, to account for (2) and (3), one might consider that an unspecified mechanism selects the particles to be accelerated, possibly according to their first ionization potential (Cassé 1979 and references there-in).

scholarly journals The cycling of carbon into and out of dust

2014 ◽  
Vol 168 ◽  
pp. 313-326 ◽  
Author(s):  
Anthony P. Jones ◽  
Nathalie Ysard ◽  
Melanie Köhler ◽  
Lapo Fanciullo ◽  
Marco Bocchio ◽  
...  
Keyword(s):  
Optical Properties ◽  
Cosmic Rays ◽  
Shock Waves ◽  
Interstellar Medium ◽  
Gas Phase ◽  
Molecular Clouds ◽  
Observational Evidence ◽  
Electron Collisions ◽  
Uv Photons ◽  
Dust Evolution

Observational evidence seems to indicate that the depletion of interstellar carbon into dust shows rather wide variations and that carbon undergoes rather rapid recycling in the interstellar medium (ISM). Small hydrocarbon grains are processed in photo-dissociation regions by UV photons, by ion and electron collisions in interstellar shock waves and by cosmic rays. A significant fraction of hydrocarbon dust must therefore be re-formed by accretion in the dense, molecular ISM. A new dust model (Jones et al., Astron. Astrophys., 2013, 558, A62) shows that variations in the dust observables in the diffuse interstellar medium (nH ≤ 103 cm−3), can be explained by systematic and environmentally-driven changes in the small hydrocarbon grain population. Here we explore the consequences of gas-phase carbon accretion onto the surfaces of grains in the transition regions between the diffuse ISM and molecular clouds (e.g., Jones, Astron. Astrophys., 2013, 555, A39). We find that significant carbonaceous dust re-processing and/or mantle accretion can occur in the outer regions of molecular clouds and that this dust will have significantly different optical properties from the dust in the adjacent diffuse ISM. We conclude that the (re-)processing and cycling of carbon into and out of dust is perhaps the key to advancing our understanding of dust evolution in the ISM.

scholarly journals Shock identification and classification in 2D magnetohydrodynamiccompressible turbulence—Orszag–Tang vortex

2021 ◽  
Vol 2 ◽  
Author(s):  
Ben Snow ◽  
Andrew Hillier ◽  
Giulia Murtas ◽  
Gert J. J. Botha
Keyword(s):  
Shock Waves ◽  
Interstellar Medium ◽  
Magnetic Reconnection ◽  
Solar Atmosphere ◽  
Full Range ◽  
Potential Mechanism ◽  
Mhd Turbulence ◽  
Mhd System

Abstract Compressible magnetohydrodynamic (MHD) turbulence is a common feature of astrophysical systems such as the solar atmosphere and interstellar medium. Such systems are rife with shock waves that can redistribute and dissipate energy. For an MHD system, three broad categories of shocks exist (slow, fast, and intermediate); however, the occurrence rates of each shock type are not known for turbulent systems. Here, we present a method for detecting and classifying the full range of MHD shocks applied to the Orszag–Tang vortex. Our results show that the system is dominated by fast and slow shocks, with far less-frequent intermediate shocks appearing most readily near magnetic reconnection sites. We present a potential mechanism that could lead to the formation of intermediate shocks in MHD systems, and study the coherency and abundances of shocks in compressible MHD turbulence.

Experimental study of heat transfer in the boundary layer of a flat plate with the impact of weak shock waves on the leading edge

2020 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Shock Waves ◽  
Flat Plate ◽  
Leading Edge ◽  
Weak Shock ◽  
The Impact

Effects of Viscosity on Steady Reflection of Weak Shock Waves

2008 ◽  
Author(s):  
Mikhail Ivanov ◽  
Yevgeny Bondar ◽  
Dmitry Khotyanovsky ◽  
Alexey Kudryavtsev ◽  
Georgiy Shoev
Keyword(s):  
Shock Waves ◽  
Weak Shock

scholarly journals Astrophysical MHD turbulence: confluence of observations, simulations, and theory

2012 ◽  
Vol 8 (S294) ◽  
pp. 325-336 ◽  
Author(s):  
Blakesley Burkhart ◽  
Alex Lazarian
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Magnetic Reconnection ◽  
Particle Transport ◽  
Recent Progress ◽  
Critical Component ◽  
Dynamo Theory ◽  
Mhd Turbulence ◽  
The Galaxy

AbstractMagnetohydrodynamic (MHD) turbulence is a critical component of the current paradigms of star formation, dynamo theory, particle transport, magnetic reconnection and evolution of the ISM. In order to gain understanding of how MHD turbulence regulates processes in the Galaxy, a confluence of numerics, observations and theory must be imployed. In these proceedings we review recent progress that has been made on the connections between theoretical, numerical, and observational understanding of MHD turbulence as it applies to both the neutral and ionized interstellar medium.

On the propagation of weak shock waves in compressible thermohyperelastic solids

2017 ◽  
Vol 229 (1) ◽  
pp. 87-97 ◽  
Author(s):  
Hocine Bechir ◽  
Abdelhakim Benslimane
Keyword(s):  
Shock Waves ◽  
Weak Shock
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