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In research published in this week's edition of nature astronomers have reported the discovery of an unusually heavy variety of ammonia that may help scientists explain the origins of materials found in asteroids and comets. Ammonia consists of a nitrogen atom surrounded by three hydrogen atoms, however, in the molecule discovered in the giant molecular-cloud NGC 1333 in the constellation of Perseus all three hydrogen are replaced by deuterium, the heavier isotope of hydrogen. Astronomers Floris van der Tak and Peter Schilke, of the Max Plank Institute for Radio Astronomy in Germany, discovered the molecule from its characteristic signal at a frequency of 309909.4 Megahertz using observations at ultrahigh radio frequencies. The chances for all three hydrogen atoms in an ammonia molecule to be replaced by the very rare deuterium atoms are one in a million billion and it is only at the very low temperatures within giant molecular clouds, of 10 degrees above absolute zero, that such high enrichments of deuterium are found. The researchers say that the presence of heavy ammonia will allow the reactions that occur at these ultralow temperatures to be identified.
High levels of deuterium in organic molecules are also found within meteorites and cosmic dust from carbon-rich asteroids and comets. Carbonaceous materials within these objects contain many complex organic molecules, including amino acids and sugars that are the building blocks of proteins and DNA, and may have played a role in the origins of life. The high deuterium to hydrogen content of these organic molecules suggests they ultimately were formed within the depths of giant molecular clouds.
More info: Nature
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