Winds of low-metallicity OB-type stars: HST-COS spectroscopy in IC1613
  We present the first quantitative UV spectroscopic analysis of resolved OB
stars in IC1613. Because of its alleged very low metallicity (<~1/10 Zo, from
HII regions), studies in this Local Group dwarf galaxy could become a
significant step forward from the SMC towards the extremely metal-poor massive
stars of the early Universe. We present HST-COS data covering the
~1150-1800{\AA} wavelength range with resolution R~2500. We find that the
targets do exhibit wind features, and these are similar in strength to SMC
stars. Wind terminal velocities were derived from the observed PCygni profiles
with the SEI method. The vinf-Z relationship has been revisited. The terminal
velocity of IC1613 O-stars is clearly lower than Milky Way counterparts, but
there is no clear difference between IC1613 and SMC or LMC analogue stars. We
find no clear segregation with host galaxy in the terminal velocities of
B-supergiants, nor in the vinf/vesc ratio of the whole OB star sample in any of
the studied galaxies. Finally, we present first evidence that the Fe-abundance
of IC1613 OB stars is similar to the SMC, in agreement with previous results on
red supergiants. With the confirmed ~1/10 solar oxygen abundances of
B-supergiants, our results indicate that IC1613's [alpha/Fe] ratio is
sub-solar.
