Bw. Miller, THE STAR-FORMATION HISTORIES OF SCULPTOR GROUP DWARF GALAXIES .1. CURRENT STAR-FORMATION RATES AND OXYGEN ABUNDANCES, The Astronomical journal, 112(3), 1996, pp. 991-1008
We present H alpha and [O III] imaging and nebular spectroscopy of H I
I regions in Sculptor Group dwarf galaxies. Of the eight galaxies in t
he sample, only two, E471-G06 and A143, have detected H II regions. Th
e H II region luminosity and size distributions for A143 are consisten
t with those seen in other dwarf galaxies. Electron densities, filling
factors and emission measures are similar to those measured in other
galaxies at similar distances but vary significantly from compact H II
regions in the Magellanic clouds. Oxygen line ratios are used to dete
rmine the oxygen abundances and ionization parameters. The oxygen abun
dances are typically similar to 0.1 solar and are consistent with the
O/H, M(B) relation. Comparison of the star formation timescales in Scu
lptor, M81, and Local Groups shows that the higher density M81 Group h
as many more galaxies forming stars at an above average rate. This is
evidence that local galaxy density can have a measurable effect on cur
rent star formation. However, a single O/H, M(B) relation seems to hol
d for all environments, so galaxy mass still appears to be the primary
factor governing a galaxy's chemical evolution. (C) 1996 American Ast
ronomical Society.