Possible cosmological implications of a hotter temperature scale for halo stars

Details Possible cosmological implications of a hotter temperature scale for halo stars Possible cosmological implications of a hotter temperature scale for halo stars

Mar 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994aj....107.1165k&link_type=abstract

Astronomical Journal (ISSN 0004-6256), vol. 107, no. 3, p. 1165-1174

Mathematics

Logic

6

Abundance, Age Factor, Astronomical Models, Cosmology, Globular Clusters, Halos, Stars, Stellar Temperature, Temperature Scales, Astronomical Spectroscopy, Balmer Series, Isochromatics, Parameterization

Scientific paper

Possible cosmological implications of a recently proposed hotter Teff scale for field halo star HD 89499; Teff values derived from Balmer line modeling for two halo stars; and temperatures derived using transformation from two independent sets of widely used isochrones, is presented which supports the need for such an upward revision in the Teff scale. Additionally, we note that the hotter temperature scale is consistent with the Bell & Gustafsson (1989) relations. Temperatures inferred from both the Victoria and Yale isochrone color-Teff conversions seem to be in good agreement with the revised Teff scale for field stars on the upper main sequence and subgiant branch. We conclude that no significant downward revision of globular cluster turnoff ages would result for those clusters having (Fe/H) near -1.3. A similarly strong conclusion cannot be reached for clusters of other metallicities, but it seems likely that no substantial age reductions (approximately greater than 1 Gyr), due to uncertainties in color-Teff relations, are necessary. Although large uncertainties in low mass stellar models are present, the good agreement between the new Yale isochrones (which are redder than the Victoria isochrones for 0.45 approximately less than (B - V) approximately less than 0.75) and the observed lower main sequence of M92 seems to be consistent with the somewhat larger upward revisions for the temperatures of cooler field stars that has been advocated. The high Teff scale leads to a mean Li-7 abundance of 2.28 +/- 0.09 (1 standard deviation) in hotter halo stars. Then, a conservative minimal primordial value of N (Li) =2.35 is inferred. When this value is combined with recent estimates of the primordial He-4 abundance, not taking into account the observational and model errors, and the limit set by the primordial D + He-3 abundance, inconsistency with standard Big Bang nucleosynthesis models occurs. However, if the observational and theoretical uncertainties are included, consistency with the standard model is still possible in the range 0.012 less than or equal to Omegab less than or equal to 0.017 (for Hzero = 100 km/s/Mpc). The higher Teff scale raises the observed B/Be ratio in HD 140283 from 10 to 12. This new value is more comfortably consistent with production of the observed B and Be by ordinary spallation processes, but does not preclude a significant primordial component in more metal-poor stars.

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