Δ Y/Δ Z from fine structure in the main sequence based on Hipparcos parallaxes |
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Authors: | B E J Pagel & L Portinari |
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Institution: | NORDITA, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark,;Dipartimento di Astronomia, Vicolo dell'Osservatorio 5, 35122 Padova, Italy |
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Abstract: | The slope Δ Y /Δ Z is a quantity of interest in relation to stellar evolution, the initial mass function and the determination of the primordial helium abundance. In this paper we estimate Δ Y /Δ Z from fine structure in the main sequence of nearby stars from Hipparcos data for stars with Z ≤ Z⊙. We find a value of about 3, which is consistent with what has been found in extragalactic H II regions and with stellar models for suitable upper limits to the initial masses of supernovae according to the initial mass function slope adopted. |
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Keywords: | stars: abundances stars: evolution ISM: abundances galaxies: abundances |
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