High-velocity clouds

@inproceedings{Wakker1991HighvelocityC,
  title={High-velocity clouds},
  author={Bart P. Wakker},
  year={1991}
}
▪ Abstract High-velocity clouds (HVCs) consist of neutral hydrogen (HI) at velocities incompatible with a simple model of differential galactic rotation; in practice one uses vLSR 90 km/s to define HVCs. This review describes the main features of the sky and velocity distributions, as well as the available information on cloud properties, small-scale structure, velocity structure, and observations other than in 21-cm emission. We show that HVCs contain heavy elements and that the more prominent… Expand

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References

SHOWING 1-10 OF 205 REFERENCES
DISTRIBUTION AND ORIGIN OF HIGH-VELOCITY CLOUDS .3. CLOUDS, COMPLEXES AND POPULATIONS
We present the first complete catalogue of high-velocity clouds (HVCs), followed by a classification of these clouds into complexes and populations. The catalogue will form the basis for comparisonsExpand
Westerbork observations of high-velocity clouds. Discussion
Six high-velocity cloud fields were observed with 1' and 1 km s-1 resolution, using the Westerbork Synthesis Radio Telescope. The structures seen in earlier observations at 10' resolution break upExpand
Velocity structures of gas in the lines of sight to the Magellanic Clouds
The results of a survey of visual absorption lines (Ca K and Na D) in the spectra of stars in the Large and Small Magellanic Clouds and in foreground objects is brought together with existingExpand
CO and IRAS detection of an intermediate-velocity cloud
In the course of a radio survey of high-Galactic-latitude clouds, CO emission was detected at the position l = 210.8 deg and b = 63.1 deg with an LSR velocity of -39 km/sec. This molecular cloudExpand
Composition of interstellar clouds in the disk and halo. I - HD 93521
In this paper we continue our investigation of diffuse clouds in the interstellar medium with an analysis of the line of sight toward the star HD 215733, located in the Galactic halo some 1700 pcExpand
H I absorption limits and emission mapping for high-velocity clouds
Systematic emission and absorption surveys have been conducted for high-velocity H I in the direction of 63 bright continuum sources. High-velocity emisison is detected along 18 of these 63Expand
Structure of the interstellar medium in the Magellanic Clouds
Using optical and UV observations, the internal gas structure of Magellanic Clouds (MCs) was examined for clues to the recent evolution of the Magellanic System and further signs of this collisionExpand
A SEARCH FOR DUST IN HIGH-VELOCITY CLOUDS
IRAS observations are used to look for infrared emission from dust in high-velocity clouds (HVCs). None of these clouds is detected. The upper limit that can be set on the IR emission per hydrogenExpand
Are there really intergalactic hydrogen clouds in the Sculptor group
High-sensitivity 21 cm observations of the region of the Sculptor group of galaxies reveal at least 30 H I clouds distributed over only the southern sector of the group. These new data add twoExpand
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