Cosmological and Chemical Evolution Implications of New ${\rm {}^3He}$ Abundances
Session 115 -- Cosmology and Dark Matter
Oral presentation, Saturday, January 15, 10:15-11:45, Salon III Room (Crystal Gateway)

## [115.04] Cosmological and Chemical Evolution Implications of New ${\rm {}^3He}$ Abundances

R.T.Rood (UVa), T.M.Bania, D.S.Balser (BU)

Bania et al. and Balser et al. at this meeting report abundances of ${\rm {}^3He}$ ranging from ${\rm {}^3He/H} \sim 1$ -- $4 \times 10^{-5}$. Here we consider the consequences of those abundances for the chemical evolution of the Galaxy and for cosmological nucleosynthesis. Since the abundance pattern does not fit the pattern expected from the overall chemical enrichment of the Galaxy, we suggest local enrichment of some H II regions perhaps from Wolf-Rayet winds. If averaged over an initial mass function stars are not a net sink for ${\rm {}^3He}$, then the abundance of our lowest abundance source places a lower limit on the cosmological parameter $\eta$, the baryon to photon ratio. The lower limit from ${\rm {}^3He}$ is about the same as the upper limit from ${\rm {}^2H}$, ${\rm {}^4He}$ and ${\rm {}^7Li}$ and resulting in a narrow band of acceptable $\eta \sim 4 \times 10^{-5}$.