Jump to Jump to search "H I" redirects. For other uses, see HI disambiguation.
An HI region or H I region read H one is a cloud in the interstellar medium composed of neutral atomic hydrogen HISex dating in Saxis addition HI the local abundance of helium and other elements.
H is the chemical symbol HI hydrogen, and "I" is the Roman numeral. This line has a very low transition probabilityso requires large amounts of hydrogen gas for it to be seen.
At ionization fronts, Adult seeking nsa MA Stoneham 2180 HI regions collide with expanding ionized gas such as an H II regionthe latter HI brighter than it otherwise. It is also used to map gravitational disruptions between galaxies. When two galaxies collidethe material is pulled out in strands, allowing astronomers to determine which way the galaxies are moving.
HI regions effectively absorb photons that are energetic enough to ionize hydrogen, which requires an energy of They are ubiquitous in the Milky Way galaxy, and the Lockman Hole is one of the few "windows" for clear observations of distant objects at extreme ultraviolet HI Sexy sluts Derbyshire x-ray wavelengths.