Abstract
A recent paper by Mr. F. Hoyle introduces some revolutionary conceptions regarding the internal constitution of the stars (Mon. Not. Roy. Ast. Soc., 106, 4; 1947). Until comparatively recently it was usually assumed that the stars contain about 30 per cent of hydrogen and 10 per cent of the heavy elements; but an accumulation of observational evidence during the last fifteen years indicates that this proportion of the heavy elements is much too high. Hoyle shows that the data are more consistent with the view that, at the time of condensation of the stars, 99 per cent, and probably more than this, must have been in the form of hydrogen, the remainder consisting of heavy elements. The mean molecular weight of a star at the time of condensation must have been about 0·5, and a subsequent increase in this could arise only by the conversion of hydrogen into helium by thermonuclear reactions. In the case of small stars like the sun, very little change in composition has taken place during their life times, so that the sun would now consist almost entirely of hydrogen. This constitution differs so widely from that of the earth, which contains very little hydrogen, that it is impossible to accept the view (now somewhat discredited) that the earth and other planets once formed part of the sun. The high ratio of hydrogen to metals in interstellar matter, obtained in 1939 by Dunham, is, Hoyle points out, a powerful argument in favour of his supernova theory of the origin of the solar system, which was developed in Mon. Not. Roy. Astro. Soc., 105, 175 (1945), and of which a short account appeared in Nature, 157, 881 (1946).
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Chemical Composition of the Stars. Nature 160, 744 (1947). https://doi.org/10.1038/160744c0
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DOI: https://doi.org/10.1038/160744c0