September 11, 2013
Astronomers Map Milky Way’s Galactic Clouds
[ Watch the Video: Mapping Our Milky Way Galaxy ]
Lee Rannals for redOrbit.com - Your Universe Online
The team from the University of New South Wales (UNSW) wrote in the journal Publications of the Astronomical Society of Australia that they are mapping the location our galaxy's galactic clouds which can be up to 100 light years across. These mysterious objects are made of up carbon monoxide, which is the second most abundant molecule in space and the easiest to see.
"One of the largest unresolved mysteries in galactic astronomy is how these giant, diffuse clouds form in the interstellar medium. This process plays a key role in the cosmic cycle of birth and death of stars," Professor Michael Burton of the UNSW School of Physics, who leads the team, said in a statement.
The researchers are also searching for "dark" galactic gas clouds, which are unseen clouds that contain very little carbon monoxide. Scientists believe these clouds are mostly made up of molecular hydrogen, which is too cold to detect. Astronomers are using telescopes in Antarctica and Chile to search for these dark clouds, based on the presence of carbon atoms rather than carbon-containing molecules.
"Taken together, these three surveys will provide us with a picture of the distribution and movement of gas clouds in our galaxy," says Burton.
If they find dark clouds, it could be the 'missing' source of gamma-rays, which are produced when high-energy cosmic rays interact with the nuclei of gas atoms or molecules they encounter while traveling through space.
"The source of more than 30 percent of gamma rays remains unidentified – another big mystery our research could throw light on," says Professor Burton.
Large giant molecular clouds could form because the gravitational collapse of an ensemble of small clouds into a larger one, or the random collision of small clouds. Stars that collapse and die help to replenish the gas clouds, as well as move around the gas and mix it up.
In May astronomers said they found clouds of hydrogen gas lurking between some of our neighboring galaxies. This discovery suggests that these clouds are independent entities and are not the far-flung suburbs of other galaxies. The team said that these clouds may be just the first examples of a larger population out there waiting to be discovered.