Intermediate-Velocity Gas in the Canadian Galactic Plane Survey
Abstract
We present observations of intermediate-velocity clouds (IVCs) found at positive velocities in the Canadian Galactic Plane Survey Phase I region (74deg<l<148deg, -3.5d<b<+5.6d). A catalog of 138 distinct IVCs and 13 IVC complexes has been compiled. From the global characteristics of our sample we demonstrate that the majority of these IVCs are directly associated with energetic phenomena, such as supernova explosions and massive star-forming regions, within the disk of the Galaxy and thus form a different population than the high-velocity clouds and high-latitude IVCs. We report what we believe to be the first detection of H I 21 cm absorption of a background source by an IVC and attempt to determine its physical properties and distance. We discuss in some detail a few of the IVCs that illustrate the connection between the clouds and energetic phenomena in the Galaxy. We suggest that the velocity shift of these IVCs away from the bulk of the Galactic H I emission provides an opportunity to study the structure of the low-latitude H I emission in a relatively confusion-free environment and present two examples of large (degree-scale) complexes of H I emission particularly suitable for such studies.
- Publication:
-
The Astronomical Journal
- Pub Date:
- March 2006
- DOI:
- 10.1086/500194
- Bibcode:
- 2006AJ....131.1501K
- Keywords:
-
- Galaxy: Structure;
- ISM: Clouds;
- ISM: Structure;
- Radio Lines: ISM;
- Surveys