Giant Molecular Clou1

Giant Molecular Clou1 - such as methanol and acetone. Radio...

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Giant Molecular Cloud A giant molecular cloud is a large, dense gas cloud (with dust) that is cold enough for molecules to form. Thousands of giant molecular clouds exist in the disk part of our galaxy. Each giant molecular cloud has 100,000's to a few million solar masses of material. AAO source One nearby example is the Orion Molecular Cloud Complex that stretches from the belt of the Orion constellation to his sword of which the Orion Nebula is a part. The Orion Complex is about 1340 light years away, several hundred light years across, and has enough material to form many tens of thousands of suns. The giant molecular clouds have dust in them to shield the densest parts of them from the harsh radiation of nearby stars so that molecules can form in them. Therefore, they are very dark and very cold with a temperature of only about 10 K. In addition to the most common molecule, molecular hydrogen, over 80 other molecules have been discovered in the clouds from simple ones like carbon monoxide to complex organic molecules
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Unformatted text preview: such as methanol and acetone. Radio telescopes are used to observe these very dark, cold clouds. The clouds are dense relative to the rest of the gas between the stars but are still much less dense than the atmosphere of a planet. Typical cloud densities are 100 to 1000 molecules per cubic centimeter while each cubic centimeter of the air you breath has about 2.5 10 19 molecules---a molecular cloud is tens to hundreds of times "emptier" than the best vacuum chambers we have on Earth! In the parts of a giant molecular cloud where very hot stars (O and B-type) have formed, the hydrogen gas surrounding them can be made to glow in the visible band to make what is called a H II region . The Orion Nebula is an example of this. It is the fuzzy patch you can see in the sword part of the Orion constellation. It is a bubble about 26 light years across that has burst out of one side of the Orion Complex....
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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