Martin wrote:
Is there an explanation for how ionized hydrogen clouds can be found so far from the galactic plane? Thanks
https://en.wikipedia.org/wiki/H_II_region wrote:
<<An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically a cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic cm. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas-Claude Fabri de Peiresc by telescope, the first such object discovered.
They may be of any shape, because the distribution of the stars and gas inside them is irregular. The short-lived blue stars created in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. They often appear clumpy and filamentary, sometimes showing bizarre shapes such as the Horsehead Nebula. H II regions may give birth to thousands of stars over a period of several million years. In the end, supernova explosions and strong stellar winds from the most massive stars in the resulting star cluster will disperse the gases of the H II region, leaving behind a cluster of stars which have formed, such as the Pleiades.
H II regions can be observed at considerable distances in the universe, and the study of extragalactic H II regions is important in determining the distance and chemical composition of galaxies. Spiral and irregular galaxies contain many H II regions, while elliptical galaxies are almost devoid of them. In spiral galaxies, including our Milky Way, H II regions are concentrated in the spiral arms, while in irregular galaxies they are distributed chaotically. Some galaxies contain huge H II regions, which may contain tens of thousands of stars. Examples include the 30 Doradus region in the Large Magellanic Cloud and NGC 604 in the Triangulum Galaxy.>>
https://en.wikipedia.org/wiki/Molecular_cloud wrote:
<<A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen (H
2). This is in contrast to other areas of the interstellar medium that contain predominantly ionized gas.
Molecular hydrogen is difficult to detect by infrared and radio observations, so the molecule most often used to determine the presence of H
2 is
carbon monoxide (CO). The ratio between CO luminosity and H
2 mass is thought to be constant, although there are reasons to doubt this assumption in observations of some other galaxies.
Within molecular clouds are regions with higher density, where lots of dust and gas cores reside, called clumps. These clumps are the beginning of star formation, if gravity can overcome the high density and force the dust and gas to collapse.>>
[quote="Martin"]
Is there an explanation for how ionized hydrogen clouds can be found so far from the galactic plane? Thanks[/quote][quote=" https://en.wikipedia.org/wiki/H_II_region"]
<<An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically a cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic cm. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas-Claude Fabri de Peiresc by telescope, the first such object discovered.
They may be of any shape, because the distribution of the stars and gas inside them is irregular. The short-lived blue stars created in these regions emit copious amounts of ultraviolet light that ionize the surrounding gas. H II regions—sometimes several hundred light-years across—are often associated with giant molecular clouds. They often appear clumpy and filamentary, sometimes showing bizarre shapes such as the Horsehead Nebula. H II regions may give birth to thousands of stars over a period of several million years. In the end, supernova explosions and strong stellar winds from the most massive stars in the resulting star cluster will disperse the gases of the H II region, leaving behind a cluster of stars which have formed, such as the Pleiades.
H II regions can be observed at considerable distances in the universe, and the study of extragalactic H II regions is important in determining the distance and chemical composition of galaxies. Spiral and irregular galaxies contain many H II regions, while elliptical galaxies are almost devoid of them. In spiral galaxies, including our Milky Way, H II regions are concentrated in the spiral arms, while in irregular galaxies they are distributed chaotically. Some galaxies contain huge H II regions, which may contain tens of thousands of stars. Examples include the 30 Doradus region in the Large Magellanic Cloud and NGC 604 in the Triangulum Galaxy.>>[/quote][quote=" https://en.wikipedia.org/wiki/Molecular_cloud"]
[float=right][img3="[color=#0000FF][size=200]The FUGIN Sky[/size]
[size=150]F[/size][size=75]our-beam receiver system[/size] [size=150]U[/size][size=75]nbiased [/size][size=150]G[/size][size=75]alactic-plane [/size][size=150]I[/size][size=75]maging survey with the [/size][size=150]N[/size][size=75]obeyama 45-m telescope.[/size][/color]"]https://pbs.twimg.com/media/DUa_0OnXUAEI6I3.jpg[/img3][/float]<<A molecular cloud, sometimes called a stellar nursery (if star formation is occurring within), is a type of interstellar cloud, the density and size of which permit the formation of molecules, most commonly molecular hydrogen (H[sub]2[/sub]). This is in contrast to other areas of the interstellar medium that contain predominantly ionized gas.
Molecular hydrogen is difficult to detect by infrared and radio observations, so the molecule most often used to determine the presence of H[sub]2[/sub] is [url=https://www.universetoday.com/138394/detailed-map-ever-made-milky-way-radio-waves/]carbon monoxide (CO)[/url]. The ratio between CO luminosity and H[sub]2[/sub] mass is thought to be constant, although there are reasons to doubt this assumption in observations of some other galaxies.
Within molecular clouds are regions with higher density, where lots of dust and gas cores reside, called clumps. These clumps are the beginning of star formation, if gravity can overcome the high density and force the dust and gas to collapse.>>[/quote]