H I region
An HI region or H I region (read H one) is a
isothermal, except near an expanding H II region.[3] Near an expanding H II region is a dense HI region, separated from the undisturbed HI region by a shock front and from the H II region by an ionization front.[3]
Mapping
Mapping HI emissions with a radio telescope is a technique used for determining the structure of spiral galaxies. It is also used to map gravitational disruptions between galaxies. When two galaxies collide, the material is pulled out in strands, allowing astronomers to determine which way the galaxies are moving.
HI regions effectively absorb
soft x-ray
wavelengths.
See also
References
- ^ "Thermal Radio Emission from HII Regions". National Radio Astronomy Observatory (US). Archived from the original on 27 September 2016. Retrieved 7 October 2016.
- .
- ^ doi:10.1086/146109.
- Anderson, Kevin J & Churchwell, Ed (1985). "The Anatomy of a Nebula". Astronomy. 13: 66–71. Bibcode:1985Ast....13...66C.
| Visible nebula | |
|---|---|
| Pre-stellar nebulae |
|
| Stellar nebula | |
| Post-stellar nebulae | |
| Clouds | |
| Morphology | |
| Intergalactic blobs | |
 Lists |
|
| Related | |
