ICRAR: Scientists Discover More about the Ingredients for Star Formation

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bystander
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ICRAR: Scientists Discover More about the Ingredients for Star Formation

Post by bystander » Tue Oct 10, 2017 2:33 pm

Scientists Discover More about the Ingredients for Star Formation
International Center for Radio Astronomy Research | 2017 Oct 10
[img3="Comparison between the stellar (top) and molecular hydrogen (bottom) distribution in very gas-rich galaxies three billion years younger than the Milky Way. Optical data is from the Sloan Digital Survey whereas molecular hydrogen maps have been obtained using the Atacama Large Millimetre Array."]https://s3-ap-southeast-2.amazonaws.com ... images.jpg[/img3][hr][/hr]
Astronomers have shed fresh light on the importance of hydrogen atoms in the birth of new stars.

Only hydrogen molecules are thought to directly fuel star formation but research published today shows there are more hydrogen atoms than molecules even in young galaxies that are making a lot of stars. ...

In the local Universe close to us about 70 per cent of the hydrogen gas is found in individual atoms, while the rest is in molecules.

Astronomers had expected that as they looked back in time, younger galaxies would contain more and more molecular hydrogen until it dominated the gas in the galaxy. Instead, they found that atomic hydrogen makes up the majority of gas in younger galaxies too. ...

ALMA Shows that Gas Reservoirs of Star-Forming Disks over the
Past 3 Billion Years Are Not Predominantly Molecular
- Luca Cortese, Barbara Catinella, Steven Janowiecki
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neufer
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Re: ICRAR: Scientists Discover More about the Ingredients for Star Formation

Post by neufer » Tue Oct 10, 2017 3:08 pm

bystander wrote:Scientists Discover More about the Ingredients for Star Formation
International Center for Radio Astronomy Research | 2017 Oct 10
Astronomers had expected that as they looked back in time, younger galaxies would contain more and more molecular hydrogen until it dominated the gas in the galaxy. Instead, they found that atomic hydrogen makes up the majority of gas in younger galaxies too. ...
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 (H2). 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 H2 is carbon monoxide (CO). The ratio between CO luminosity and H2 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.>>
Art Neuendorffer

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