ISSN:
1572-9672
Keywords:
galaxies: abundances
;
ISM: abundances
;
stars: abundances
;
stars: evolution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract The primordial helium abundance YP is important for cosmology and the ratio ΔY/ΔZ of the changes relative to primordial abundances constrains models of stellar evolution. While the most accurate estimates of YP come from emission lines in extragalactic H II regions, they involve an extrapolation to zero metallicity which itself is closely tied up with the slope ΔY/ΔZ. Recently certain systematic effects have come to light in this exercise which make it useful to have an independent estimate of ΔY/ΔZ from fine structure in the main sequence of nearby stars. We derive such an estimate from Hipparcos data for stars with Z ≤ Z⊙ and find values between 2 and 3, which are consistent with stellar models, but still have a large uncertainty.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005098630276
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