Surprising telescope observations shake up galactic formation theories

ToSeek · #1 (**permalink**) 14-August-2006, 08:27 PM

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A heavy form of hydrogen created just moments after the Big Bang has been found to exist in larger quantities than expected in the Milky Way, a finding that could radically alter theories about star and galaxy formation, says a new international study led by the University of Colorado at Boulder.

Blob · #2 (**permalink**) 14-August-2006, 10:04 PM

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A heavy form of hydrogen created just moments after the Big Bang has been found to exist in larger quantities than expected in the Milky Way, a finding that could radically alter theories about star and galaxy formation

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The detection of deuterium is of interest because the amount of deuterium can be related to the amount of Dark Matter in the universe.
Also, the brightness-temperature fluctuations due to resonant absorption of CMB photons in the 21-cm line of neutral hydrogen with those due to resonant absorption of CMB photons in the 92-cm line of neutral deuterium is proportional to the fossil deuterium to hydrogen ratio fixed during big bang nucleosynthesis; which puts constraints to the baryon density of the Universe.

Blob · #3 (**permalink**) 15-August-2006, 02:22 AM

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The researchers identified dusty, relatively undisturbed regions by searching for low levels of gaseous silicon and iron – these elements had presumably condensed into solid dust grains. The deuterium to hydrogen ratio in these dusty regions was as low as 5 parts per million (ppm).
According to Jeffrey Linsky of the JILA research institute in Boulder, Colorado, US, the most likely explanation for the higher ratio is that the galaxy has absorbed a lot more "pristine" gas – which has not been altered much by stars – than previously believed.

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Last year Fuse measured the total ratio of deuterium to hydrogen in gas between stars (out to 3,000 light years from the sun) at 23 parts per million. That ratio is only slightly smaller than the best estimates of the ratio at the beginning of the universe, which was about 28 parts per million.
Correspondingly, Alan E. E. Rogers and colleagues at Massachusetts Institute of Technology's (MIT) Haystack Observatory in Westford, Massachusetts also measured the deuterium-to-hydrogen ratio as 23 parts per million, which is close to the Wilkinson Microwave Anisotropy Probe prediction of 25 parts per million.

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