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Isolating Clusters with Wolf-Rayet Stars in I Zw 18

Thomas M. Brown·Sara R. Heap·Ivan Hubeny·Thierry Lanz·Don Lindler
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Abstract

We present UV images and spectra of the starburst galaxy I Zw 18, taken with the Space Telescope Imaging Spectrograph. The high spatial resolution of these data allows us to isolate clusters containing Wolf-Rayet stars of the subtype WC. Our far-UV spectra clearly show CIV 1548,1551 and HeII 1640 emission of WC stars in two clusters: one within the bright (NW) half of I Zw 18, and one on the outskirts of this region. The latter spectrum is unusual, because the CIV is seen only in emission, indicating a spectrum dominated by WC stars. These data also demonstrate that the HI column in I Zw 18 is strongly peaked in the fainter (SE) half of I Zw 18, with a column depth far larger than that reported in previous analyses.

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Thomas M. Brown, Sara R. Heap, Ivan Hubeny, Thierry Lanz, Don Lindler. 2002-10-10. Isolating Clusters with Wolf-Rayet Stars in I Zw 18. https://doi.org/10.1086/345336

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