October 12, 2010
‘Teenage’ Galaxies Booming With Star Births
Scientists from the Niels Bohr Institute have been studying distant galaxies, which are among the most active star-forming galaxies in the Universe. They form around 1,000 new stars a year "“ a 1,000 times more than our own galaxy, the Milky Way. The findings have been published in Monthly Notices of the Royal Astronomical Society.
"The galaxies are located in the far distant Universe "“ when the universe was 3 billion years old (equivalent to only 20 percent of its current age). It is a period of the Universe when the galaxies were very active, almost teenager-like and out of control", describes Thomas R. Greve, Associate professor in astrophysics at Dark Cosmology Centre, Niels Bohr Institute at the University of Copenhagen.
"We have measured the CO levels, that is to say carbon monoxide, which is one of the most common molecules in the universe, after the hydrogen molecule, H2. Using the measurements we have calculated how much gas there is in the galaxy and it turns out there are extremely large amounts of gas in these galaxies ", explains Thomas R. Greve.
Raw material for new stars
Gas is the raw material used in the Universe to form stars. In the galaxies the gas collects in large clouds, which become denser and denser as a result of their own gravitational pull. Eventually, the gas becomes so dense that it collapses into a ball of glowing gas, which forms a new star "“ the cloud almost 'explodes' in a cosmic firework display of new stars.
"What is new about our observations is that we have looked at the amount of cold, diffuse gas that is not yet actively star-forming, and what we can determine is that there is more than twice as much gas than previously thought. This means that there is an enormous amount of raw material, which can condense and form new stars ", explains Thomas R. Greve.
The measurements of the morphology of the gas also suggest that these galaxies are not only bigger than we thought, but also very irregular in their shape. It is only much later (several hundred billion years) in their development, after they have undergone their intense star formation that they become the mature, regular, elliptical shaped galaxies that we see in our Universe today.
Image Caption: This is an example of a teenage galaxy. The white contours show the new measurements of carbon emissions, which have led to a drastic reassessment of the gas mass of these young galaxies. Credit: Ivision et al. 2010
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