THE COSMIC ABUNDANCE OF HE-3 .3. IMPROVED LINE PARAMETERS FOR SELECTED SOURCES

Citation
Ds. Balser et al., THE COSMIC ABUNDANCE OF HE-3 .3. IMPROVED LINE PARAMETERS FOR SELECTED SOURCES, The Astrophysical journal, 430(2), 1994, pp. 667-681
Citations number
37
Categorie Soggetti
Astronomy & Astrophysics
Journal title
ISSN journal
0004637X
Volume
430
Issue
2
Year of publication
1994
Part
1
Pages
667 - 681
Database
ISI
SICI code
0004-637X(1994)430:2<667:TCAOH.>2.0.ZU;2-P
Abstract
We report on our progress in determining the cosmic abundance of He-3. The abundances are derived from observations of the 8.665 GHz hyperfi ne line of He-3+ in H II regions. Despite observational challenges we have measured the line to high enough precision in some H II regions t hat the line parameters are no longer the limiting factor in the accur acy of the abundance determinations. We find abundances ranging from H e-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-Ra yet winds. If averaged over an initial mass function stars are not a n et sink for He-3, then our lowest abundance source places a lower limi t on the cosmological parameter eta, the baryon-to-photon ratio. The H e-3 lower limit is about the same as the upper limit from H-2, He-4, a nd Li-7, eta approximately 4 x 10(10).