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Science Frontiers ONLINE No. 23: Sep-Oct 1982 |
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Where are the primordial stars?
Down the years, astronomers have been able to divide almost all stars into two groups: Population I, made up of young stars enriched by the products of their ancestors; and Population II, those relatively older ancestor stars containing more hydrogen and fewer heavier elements. Population I, according to present thinking, was formed out of the "ashes" of Population-II stars. What is missing from the picture are PopulationIII stars -- stars almost devoid of elements heavier than hydrogen and helium, and formed while the Big Bang was still echoing throughout the cosmos. Current astrophysical theory requires "ashes" from Population III to create Population II. Do the astronomers find any primordial Population-III stars kicking around? Hardly a handful; not nearly enough to satisfy the prevailing model of stellar evolution. One explanation is that Population-III stars have been around long enough to collect a camouflaging veneer of metallic debris. Some astronomers surmise that Population-III stars are truly extinct for some unknown reason.
(Anonymous; "Where Is Population III?" Sky and Telescope, 64:19, 1982.)