ISSN:
1572-9672
Keywords:
3-Helium
;
cosmic abundance
;
planetary nebula
;
chemical evolution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract We report on our continuing efforts to determine 3He abundances in H II regions and planetary nebulae. Our detections of 3He in some PNe show that some stars produce large amounts of 3He. However the H II region abundances show no evidence for this production. From our sample of 〉 40 H II regions, the subsample which should yield the most reliable abundances has 3He/H abundances which scatter between 1-2 × 10-5. There is no trend with either galactocentric distance or metallicity. Even if we do not understand the underlying mechanisms, we see empirically that stars neither produce nor destroy 3He in a major way. We thus suggest that the level of the "3He Plateau" (3He/H = 1.5 -0.5 +1.0 × 10-5) is a reasonable estimate for the primordial 3He.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005023402960
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