Extragalactic high-velocity clouds - VLA observations of the broad neutral hydrogen absorption in the radio galaxy 3C 293

1985 ◽  
Vol 289 ◽  
pp. 574 ◽  
Author(s):  
A. D. Haschick ◽  
W. A. Baan
Keyword(s):  
High Velocity ◽  
Hydrogen Absorption ◽  
Radio Galaxy ◽  
Neutral Hydrogen ◽  
High Velocity Clouds

Neutral hydrogen absorption by high-velocity clouds

1978 ◽  
Vol 221 ◽  
pp. L95 ◽  
Author(s):  
H. E. Payne ◽  
J. M. Dickey ◽  
E. E. Salpeter ◽  
Y. Terzian
Keyword(s):  
High Velocity ◽  
Hydrogen Absorption ◽  
Neutral Hydrogen ◽  
High Velocity Clouds

Detection of 21-CENTIMETER Hydrogen Absorption in the High-Velocity Component of the Radio Galaxy Perseus a

1973 ◽  
Vol 185 ◽  
pp. 809 ◽  
Author(s):  
David S. de Young ◽  
Morton S. Roberts ◽  
William C. Saslaw
Keyword(s):  
Velocity Component ◽  
High Velocity ◽  
Hydrogen Absorption ◽  
Radio Galaxy

Neutral hydrogen absorption within the radio galaxy 3C 178

1978 ◽  
Vol 225 ◽  
pp. 343
Author(s):  
A. D. Haschick ◽  
W. A. Baan ◽  
B. F. Burke
Keyword(s):  
Hydrogen Absorption ◽  
Radio Galaxy ◽  
Neutral Hydrogen

Neutral hydrogen absorption in the radio galaxy 3C 293

1981 ◽  
Vol 243 ◽  
pp. L143 ◽  
Author(s):  
W. A. Baan ◽  
A. D. Haschick
Keyword(s):  
Hydrogen Absorption ◽  
Radio Galaxy ◽  
Neutral Hydrogen

scholarly journals Analysis of Low-and High-Resolution Observations of High-Velocity Clouds

1989 ◽  
Vol 120 ◽  
pp. 416-423
Author(s):  
Bart P. Wakker
Keyword(s):  
High Velocity ◽  
Galactic Center ◽  
Neutral Hydrogen ◽  
Current Status ◽  
Galactic Rotation ◽  
Single Model ◽  
Neutral Gas ◽  
The Galaxy ◽  
High Velocity Clouds ◽  
Distance Problem

For almost three decades neutral hydrogen moving at velocities unexplicable by galactic rotation has been observed. These so-called high-velocity clouds (HVCs) have been invoked as evidence for infall of neutral gas to the galaxy, as manifestations of a galactic fountain, as energy source for the formation of supershells, etc. No general consensus about their origin has presently been reached. However, it is becoming clear that no single model will suffice to explain all HVCs. A number of clouds may consist of material streaming toward the galactic center, as Mirabel (this conference) has advocated for several years, though their origin still remains unclear. A better understanding is mainly hampered by the fact that the distance remains unknown. An overview of the current status of the distance problem is given by van Woerden elsewhere in this volume.

scholarly journals Observations of high velocity HI clouds in the Local Group

1978 ◽  
Vol 79 ◽  
pp. 49-49
Author(s):  
W.K. Huchtmeier
Keyword(s):  
Radio Telescope ◽  
High Velocity ◽  
Local Group ◽  
Neutral Hydrogen ◽  
Beam Width ◽  
Late Type ◽  
M 31 ◽  
High Velocity Clouds ◽  
Half Power ◽  
Magellanic Stream

High velocity clouds (HVC) of neutral hydrogen in or around our galaxy and the observations of intergalactic HI in the Local group: Magellanic stream (Mathewson et al., 1974, Astrophys. J. 190, p. 291), M 31 (Davies, R.D., 1975, Mon. Not. R. astr. Soc., 170, p. 45P), and in the Sculptor group of galaxies (Mathewson et al., 1975, Astrophys. J. 195, p. L97) motivated us to search for HVC-phenomena in a number of nearby late-type galaxies with the 100 m Effelsberg radio telescope which has a half power beam width of 8.5′ at the wavelength of 21 cm.

Maser effects in the interstellar hydrogen clouds of the galactic halo

1967 ◽  
Vol 31 ◽  
pp. 291-293
Author(s):  
I. S. Šklovskij
Keyword(s):  
High Velocity ◽  
Population Inversion ◽  
Galactic Halo ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Collisional Excitation ◽  
Hydrogen Atoms ◽  
Hydrogen Density ◽  
The Galaxy ◽  
High Velocity Clouds

It is suggested that the neutral hydrogen atoms in clouds with high negative velocities observed at high galactic latitudes may, when moving towards a galactic H 11 region, be excited by radiation in the red wing of the Lyman-α profile. The steepness of this wing may cause a population inversion of the hyperfine-structure levels. Consequently, estimates of the hydrogen density in the high-velocity clouds, and of the flow of matter towards the galactic plane (or into the Galaxy), when based on the assumption of collisional excitation, may be too high by two orders of magnitude.

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.

Neutral hydrogen emission-absorption observations of high-velocity clouds

1980 ◽  
Vol 240 ◽  
pp. 499 ◽  
Author(s):  
H. E. Payne ◽  
Y. Terzian ◽  
E. E. Salpeter
Keyword(s):  
High Velocity ◽  
Neutral Hydrogen ◽  
Hydrogen Emission ◽  
High Velocity Clouds
Sign in / Sign up

Export Citation Format

Share Document