What is the problem with ³He?

We consider the galactic evolutionary history of ³He in models which deplete deuterium by as much as a factor of 2 to ∼15 from its primordial value to its present-day observed value in the interstellar medium (ISM). We show that when ³He production in low-mass stars (1-3 M_⊙) is included over the history of the galaxy, ³He is greatly overproduced and exceeds the inferred solar values and the abundances determined in galactic H II regions. Furthermore, the ISM abundances show a disturbing dispersion which is difficult to understand from the point of view of standard chemical evolution models. In principle, resolution of the problem may lie in either (1) the calculated ³He production in low-mass stars; (2) the observations of the ³He abundance; or (3) an observational bias toward regions of depleted ³He. Since ³He observations in planetary nebula support the calculated ³He production in low-mass stars, option (1) is unlikely. We will argue for option (3) since the ³He interstellar observations are indeed made in regions dominated by massive stars in which ³He is destroyed. In conclusion, we note that the problem with ³He seems to be galactic and not cosmological.