The role of magnetic reconnection in the interaction of high-velocity clouds and the Galactic disk

2008 ◽  
pp. 451-454 ◽  
Author(s):  
Harald Lesch ◽  
Guido T. Birk
Keyword(s):  
Magnetic Reconnection ◽  
High Velocity ◽  
Galactic Disk ◽  
High Velocity Clouds

scholarly journals The Role of Magnetic Reconnection in the Interaction of High-Velocity Clouds and the Galactic Disk

1997 ◽  
Vol 166 ◽  
pp. 451-454
Author(s):  
Harald Lesch ◽  
Guido T. Birk
Keyword(s):  
Magnetic Reconnection ◽  
High Velocity ◽  
Galactic Plane ◽  
Magnetic Energy ◽  
Galactic Disk ◽  
Ohmic Dissipation ◽  
X Ray ◽  
Gas Heating ◽  
High Velocity Clouds

AbstractThe boundaries of high-velocity-clouds that hit the Galactic plane are sources of strong X-ray emission indicating gas temperatures of a few million Kelvin. We show that numerous individual magnetic reconnection processes in the interaction region between an HVC and the ionized Reynolds layer may cause the gas heating via dynamical Ohmic dissipation. We present results of numerical plasmaneutral gas fluid simulations performed to study the dynamical reconnection process and to calculate the conversion of magnetic energy into heat.

High-energy radiation from the impact of high-velocity clouds on the galactic disk

2017 ◽  
Author(s):  
Ana Laura Müller ◽  
Gustavo Esteban Romero ◽  
Maŕıa Victoria del Valle
Keyword(s):  
High Velocity ◽  
Galactic Disk ◽  
High Energy ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
High Velocity Clouds ◽  
The Impact

scholarly journals Gamma rays from violent interstellar events

1989 ◽  
Vol 120 ◽  
pp. 494-499
Author(s):  
J.B.G.M. Bloemen
Keyword(s):  
Gamma Rays ◽  
High Velocity ◽  
Galactic Disk ◽  
Cosmic Ray ◽  
Point Sources ◽  
Prominent Feature ◽  
Hii Region ◽  
Ray Density ◽  
Γ Ray ◽  
High Velocity Clouds

SummaryAs an illustration of what the next generation of γ-ray telescopes may show us, an up-to-date COS-B ‘finding chart’ of potential γ-ray point sources and unexplained extended γ-ray features is presented. The latter, in particular, may be related to energetic phenomena in the interstellar medium, capable of enhancing the local cosmic-ray density. As an example, a prominent feature, extending over at least 10° — 15° almost perpendicular to the Galactic disk, is discussed in some detail, linking it to the giant HII region S54 and Complex C of high-velocity clouds.

The Collisions of High‐Velocity Clouds with a Magnetized Gaseous Galactic Disk

1999 ◽  
Vol 515 (2) ◽  
pp. 657-668 ◽  
Author(s):  
Alfredo Santillan ◽  
Jose Franco ◽  
Marco Martos ◽  
Jongsoo Kim
Keyword(s):  
High Velocity ◽  
Galactic Disk ◽  
High Velocity Clouds

scholarly journals HI in the galactic disk

1979 ◽  
Vol 84 ◽  
pp. 61-63
Author(s):  
F. J. Kerr
Keyword(s):  
High Velocity ◽  
Supernova Remnants ◽  
Rotation Curve ◽  
Galactic Disk ◽  
Galactic Rotation ◽  
Density Waves ◽  
Galactic Rotation Curve ◽  
High Velocity Clouds

This review of 21-cm studies of the galactic disk will be rather short, because several aspects of such studies are being covered by other speakers. These include the galactic rotation curve, the warp, the outer limits of the hydrogen layer, high-velocity clouds, large supernova remnants and comparisons between observations and theory with respect to density waves.

scholarly journals Hα Distances to High Velocity Clouds

2004 ◽  
Vol 217 ◽  
pp. 12-19
Author(s):  
Joss Bland-Hawthorn ◽  
Mary Putman
Keyword(s):  
High Velocity ◽  
Local Group ◽  
Solid Angle ◽  
Galactic Disk ◽  
Distance Constraint ◽  
Upper Limits ◽  
The Galaxy ◽  
Ionization Model ◽  
High Velocity Clouds ◽  
Magellanic Stream

Several observing teams have now obtained deep Hα spectroscopy towards high-velocity clouds (HVCs) which vary in structure from compact (CHVCs) to the Magellanic Stream. Our team has observed clouds which range from being bright (~640 mR) to having upper limits on the order of 30 to 70 mR. The Hα measurements can be interpreted as a distance constraint if we adopt a halo ionization model based on fesc ≈ 6% of the ionizing photons escaping normal to the Galactic disk (fesc ≈ 1 − 2% when averaged over solid angle). The results suggest that many HVCs and CHVCs are within a ~40 kpc radius from the Galaxy and are not members of the Local Group at megaparsec distances. We refer the reader to Putman et al. (2003) for the full version of the paper presented here.

scholarly journals High Velocity Neutral Hydrogen Clouds

1974 ◽  
Vol 60 ◽  
pp. 599-616
Author(s):  
R. D. Davies
Keyword(s):  
High Velocity ◽  
Spiral Structure ◽  
Neutral Hydrogen ◽  
Magellanic Clouds ◽  
Galactic Rotation ◽  
Velocity Pattern ◽  
Tidal Interactions ◽  
The Galaxy ◽  
High Velocity Clouds

A review is given of the observations of neutral hydrogen high velocity clouds (|ν| > 80 km s−1) in and near the Galaxy. The positive and negative clouds are seen to have different distributions in the sky, following roughly the velocity pattern of galactic rotation. A characteristic of the majority of the clouds is their distribution in elongated bands or strings. The various theories of origin of HVCs are discussed; the possible role of the tidal interactions between the Magellanic Clouds and the Galaxy is emphasized. Tests are suggested to distinguish between the Oort theory of the infall of intergalactic material and theories which envisage the HVCs as originating in the outermost spiral structure.

scholarly journals The Intermediate Velocity Cloud IVC86+38.5-45, Related to High Velocity Clouds?

1989 ◽  
Vol 120 ◽  
pp. 458-458
Author(s):  
U. Herbstmeier
Keyword(s):  
High Velocity ◽  
Galactic Disk ◽  
Dust Cloud ◽  
Galactic Latitude ◽  
High Galactic Latitude ◽  
High Velocity Clouds ◽  
Cloud Complex ◽  
Galactic Longitude ◽  
Velocity Cloud ◽  
High Velocity Cloud

Examining the high velocity cloud complex C and its possible interaction with gas of the galactic disk we became aware of a dust cloud located at galactic longitude l = 86° and latitude b = 38°.5 seen in the l00µm image of the IRAS. This cloud consists of a cucumber shaped core surounded by a horseshoe shaped halo opening towards larger galactic coordinates. At very low 100µm intensities dust lanes starting at the core or the ends of the horseshoe can be traced for about 5° towards high galactic latitude and longitude.

scholarly journals 3D Hydrodynamical Simulations of a Galactic Fountain

1997 ◽  
Vol 166 ◽  
pp. 495-498
Author(s):  
M.A. de Avillez ◽  
D.L. Berry ◽  
F.D. Kahn
Keyword(s):  
High Velocity ◽  
Galactic Halo ◽  
Galactic Disk ◽  
Unstable Layer ◽  
High Velocity Clouds ◽  
Hydrodynamical Simulations ◽  
Cold Gas

AbstractGalactic fountains are thought to be responsible for the formation of the observed intermediate and high velocity clouds in the Galactic halo. Threedimensional simulations have been carried out to determine the evolution of the disk gas as it enters the fountain, cools and returns to the Galactic disk. The descending cold gas, headed by a shock, sweeps up the ascending flow, triggering the formation of an unstable layer where Rayleigh-Taylor instabilities grow, which may provoke the formation of the observed clouds.

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