The Chemical Residue of a White Dwarf-Dominated Galactic Halo

Abstract

Halo initial mass functions (IMFs), heavily-biased toward white dwarf (WD) precursors (i.e. 1->8 M_sun), have been suggested as a suitable mechanism for explaining microlensing statistics along the line of sight to the LMC. Such IMFs can apparently be invoked without violating the observed present-day WD luminosity function. By employing a simple chemical evolution argument, we demonstrate that reconciling the observed halo Population II dwarf abundances (i.e. [C,N/O]=-0.5), with that expected from the postulated ``WD-heavy'' IMF (i.e. [C,N/O]=+0.5), is difficult.

9 pages, 5 figures, LaTeX, also available at http://msowww.anu.edu.au/~gibson/publications.html, to appear in ApJ, Part I, 1997, in press

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