MPE: Young galaxies gorge on gas

Find out the latest thinking about our universe.
Post Reply
User avatar
bystander
Apathetic Retiree
Posts: 21571
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

MPE: Young galaxies gorge on gas

Post by bystander » Wed Feb 10, 2010 6:57 pm

Young galaxies gorge on gas
Max Planck Institute for Extraterrestrial Physics - 2010 Feb 10
Scientists find explanation for higher star formation rate in young galaxies

Stars form from giant gas clouds in galaxies - the star formation rate however has changed over cosmic timescales. In the young universe many more stars were born. Scientists from the Max Planck Institute for extraterrestrial Physics, together with an international team of astronomers have found a plausible explanation: a few billion years after the Big Bang, normal star forming galaxies contained five to ten times more cold gas than today, providing more "food" to fuel the star formation process.
Image
Spatially resolved optical and millimetre images of a typical massive galaxy at redshift z=1.1 (5.5 billion years after the Big Bang). The left image was taken with the Hubble Space Telescope in the V- and I-optical bands, as part of the AEGIS survey of distant galaxies. The right image is an overlay of the CO 3-2 emission observed with the PdBI (red/yellow colours) superposed on the I-image (grey). For the first time these observations clearly show that the molecular line emission and the optical light from massive stars trace a massive, rotating disk of diameter ~60,000 light years. This disk is similar in size and structure as seen in z~0 disk galaxies, such as the Milky Way. However, the mass of cold gas is in this disk is about an order of magnitude larger than in typical z~0 disk galaxies. This explains why high-z galaxies can form continuously at about ten times the rate of typical z~0 galaxies. (Copyright: MPE/IRAM)

User avatar
bystander
Apathetic Retiree
Posts: 21571
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

SciAm: Star Mills: Ancient Galaxies Packed More Raw Material

Post by bystander » Wed Feb 10, 2010 7:26 pm

Star Mills: Ancient Galaxies Packed More Raw Material for Stellar Formation
Scientific American - 2010 Feb 10
The rapid formation of stars billions of years ago compared with the present day appears to have resulted from larger gas reservoirs rather than from a more efficient formation process.

The Milky Way Galaxy, to take a census view, is a populous place with a very low birthrate—it is home to hundreds of billions of stars, but only a handful of new ones appear each year. Neighboring galaxies show similar traits; accordingly, they must have once formed stars at a much more rapid clip. Across the universe, astronomers can see galaxies earlier in cosmic history, and unsurprisingly the birthrate then was much higher.

A new study shows that galaxies present just a few billion years after the big bang had much more star-forming material, in the form of molecular gas, to draw on. The finding, published in the February 11 issue of Nature, confirms the commonly held supposition that the vigorous star formation in the young universe largely stems from an early bounty of raw materials, rather than a more efficient process of star production. (Scientific American is part of Nature Publishing Group.)

User avatar
bystander
Apathetic Retiree
Posts: 21571
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

UA: Why Today’s Galaxies Don't Make as Many Stars

Post by bystander » Sat Feb 13, 2010 12:16 am

Why Today’s Galaxies Don't Make as Many ... ey Used To
University of Arizona News - 2010 Feb 12
University of Arizona astronomers have helped solve a mystery surrounding the birth of stars in galaxies that has long puzzled scientists. Their results are published in the Feb. 11 issue of Nature.

Post Reply