| Light
Element Abundances |
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| • | 4He:
Generally observed in hot stars and |
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| regions of
ionized hydrogen. Produced |
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| in stars,
which is a complication in |
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| determining
the primordial abundance. |
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| Technique –
determine abundance as |
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| function of
metallicity and extrapolate to |
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| zero
metallicity. See summary by Hogan |
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| (1997 – good
review of this topic), with |
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| typical
result of 0.232 uncertain by about |
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| 0.005, based
on H II regions. |
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