  Ultraviolet and 21-cm observations suggest that the extremely low-metallicity
galaxy, I Zw 18, is a stream-fed galaxy containing a "pocket" of pristine stars
responsible for producing nebular He II recombination emission observed in I
Zw18-NW. Far-UV spectra by Hubble/COS and the Far Ultraviolet Spectroscopic
Explorer (FUSE) make this suggestion conclusive by demonstrating that the
spectrum of I Zw 18-NW shows no metal lines like O VI 1032, 1038 of comparable
ionization as the He II recombination emission.
