Solutions for Chapter 13: Line Radiation of Neutral Hydrogen

2018 ◽  
pp. 153-158
Author(s):  
Thomas L. Wilson ◽  
Susanne Hüttemeister
Keyword(s):  
Neutral Hydrogen ◽  
Line Radiation

Line Radiation of Neutral Hydrogen

2008 ◽  
pp. 329-358
Author(s):  
Thomas L. Wilson ◽  
Kristen Rohlfs ◽  
Susanne Hüttemeister
Keyword(s):  
Neutral Hydrogen ◽  
Line Radiation

scholarly journals Notes on the structure of the SMC as observed in 21-cm line radiation from neutral hydrogen

1964 ◽  
Vol 20 ◽  
pp. 255-261 ◽  
Author(s):  
J. V. Hindman
Keyword(s):  
Neutral Hydrogen ◽  
Magellanic Clouds ◽  
Line Radiation

Earlier surveys of the line radiation from neutral hydrogen in the Magellanic Clouds (Kerr, Hindman, and Robinson 1954; Hindman, Kerr, and McGee 1963; Hindman et al. 1963) have shown that the amount of gas associated with these extragalactic bodies is relatively large. The gas appears widespread, surrounding the stellar bodies in a single continuous and very tenuous envelope with a marked bridge in the vicinity of the optical wing of the SMC linking the two main concentrations.

scholarly journals Theoretical Aspects of Mass Loss from Late-Type Stars

1977 ◽  
Vol 42 ◽  
pp. 577-590 ◽  
Author(s):  
Ray J. Weymann
Keyword(s):  
Mass Loss ◽  
Neutral Hydrogen ◽  
Radio Radiation ◽  
Late Type ◽  
Circumstellar Envelopes ◽  
Molecular Line ◽  
Infrared Excess ◽  
Line Radiation ◽  
Stellar Radiation ◽  
Expanding Shells

Since Deutsch’s (1956) discovery that in α Herculis the displaced circumstellar absorption lines common in the spectra of late-type giants and supergiants really represented a loss of matter, the evidence that this is a very extensive and common feature among all late giants and supergiants has become very persuasive. To the extensive optical spectroscopic evidence for mass loss from these stars originally obtained by Deutsch and subsequently by others, we may now add observations of infrared excess from dust in circumstellar envelopes (Merrill 1977), radio molecular line radiation from expanding shells (Winnburg 1971), thermal and possibly 21 cm radio radiation from ionized and neutral hydrogen respectively (Smolinski et al. 1977; Zuckerman 1977) and the direct photographs of the envelope of α Ori in the light of one of the potassium resonance lines from scattered stellar radiation (Bernat et al. 1977).

Motions of neutral hydrogen at high latitudes

1967 ◽  
Vol 31 ◽  
pp. 265-278 ◽  
Author(s):  
A. Blaauw ◽  
I. Fejes ◽  
C. R. Tolbert ◽  
A. N. M. Hulsbosch ◽  
E. Raimond
Keyword(s):  
Surface Density ◽  
Velocity Dispersion ◽  
Neutral Hydrogen ◽  
Hydrogen Gas ◽  
High Latitudes ◽  
Low Velocity

Earlier investigations have shown that there is a preponderance of negative velocities in the hydrogen gas at high latitudes, and that in certain areas very little low-velocity gas occurs. In the region 100° <l< 250°, + 40° <b< + 85°, there appears to be a disturbance, with velocities between - 30 and - 80 km/sec. This ‘streaming’ involves about 3000 (r/100)2solar masses (rin pc). In the same region there is a low surface density at low velocities (|V| < 30 km/sec). About 40% of the gas in the disturbance is in the form of separate concentrations superimposed on a relatively smooth background. The number of these concentrations as a function of velocity remains constant from - 30 to - 60 km/sec but drops rapidly at higher negative velocities. The velocity dispersion in the concentrations varies little about 6·2 km/sec. Concentrations at positive velocities are much less abundant.

Interstellar gas in the central region of the Galaxy

1967 ◽  
Vol 31 ◽  
pp. 239-251 ◽  
Author(s):  
F. J. Kerr
Keyword(s):  
Central Region ◽  
Galactic Plane ◽  
Neutral Hydrogen ◽  
Continuum Emission ◽  
Galactic Centre ◽  
Interstellar Gas ◽  
Hydrogen Recombination ◽  
The Galaxy ◽  
Centre Region ◽  
The Relationship

A review is given of information on the galactic-centre region obtained from recent observations of the 21-cm line from neutral hydrogen, the 18-cm group of OH lines, a hydrogen recombination line at 6 cm wavelength, and the continuum emission from ionized hydrogen.Both inward and outward motions are important in this region, in addition to rotation. Several types of observation indicate the presence of material in features inclined to the galactic plane. The relationship between the H and OH concentrations is not yet clear, but a rough picture of the central region can be proposed.

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