The cosmic abundance of He-3. 3. Improved line parameters for selected sources

Details The cosmic abundance of He-3. 3. Improved line parameters for selected sources The cosmic abundance of He-3. 3. Improved line parameters for selected sources

Aug 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994apj...430..667b&link_type=abstract

The Astrophysical Journal, vol. 430, no. 2, pt. 1, p. 667-681

Mathematics

Logic

73

Abundance, Galactic Evolution, H Ii Regions, Helium Isotopes, Interstellar Matter, Line Spectra, Astronomical Models, Cosmology, Nuclear Fusion, Radiation Sources, Spectrum Analysis, Star Formation

Scientific paper

We report on our progress in determining the cosmic abundance of He-3. The abundances are derived from observations of the 8.665 GHz hyperfine line of (3)He(+) in H II regions. Despite observational challenges we have measured the line to high enough precision in some H II regions that the line parameters are no longer the limiting factor in the accuracy of the abundance determinations. We find abundances ranging from He-3/H approximately 1-4 x 10-5. Since the abundance pattern does not fit that expected from the overall chemical evolution of the Galaxy, we suggest local enrichment of some H II regions, perhaps from Wolf-Rayet winds. If averaged over an intial mass function stars are not a net sink for He-3, then our lowest abundance source places a lower limit on the cosmological parameters eta the baryon-to-photon ratio. The He-3 lower limit is about the same as the upper limit from H-2, He-4 and Li-7 eta approximately 4 x 10-10.

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