Optical & NIR Surface Photometry of I Zw 18

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dc.creatorPapaderos, P.
dc.creatorIzotov, Yu. I.
dc.creatorNoeske, K. G.
dc.creatorThuan, T. X.
dc.creatorFricke, K. J.
dc.date2001-10-01
dc.date2001-10-01
dc.date.accessioned2026-07-07T02:00:30Z
dc.date.available2026-07-07T02:00:30Z
dc.descriptionUsing HST and ground-based optical and NIR data, we investigate whether the blue compact dwarf (BCD) galaxy I Zw 18 has an extended low-surface-brightness (LSB) older stellar population underlying the star-forming regions, as is the case in evolved iE/nE BCDs. Subtraction of narrow band H_alpha and [O III] exposures from R and V images shows that the filamentary LSB envelope extending out to ~2 kpc away from the starburst region, and hence the optical broad-band colors observed therein, are due mainly to ionized gas emission. Ionized gas accounts already at a galactocentric distance of 0.7 kpc for more than 80% of the R band line-of-sight intensity and contributes more than 40% of the integrated R band light of I Zw 18. The structural properties (such as the exponential scale length) of the stellar LSB component underlying the extended ionized gas emission place I Zw 18 among the most compact BCDs studied so far. Contrary to evolved nE/iE BCDs, the stellar component in I Zw 18 shows no appreciable color gradients over a range of ~8 mag in surface brightness.
dc.description4 pages, 2 figures; corrected URL of original figure 1 in the text; also available at http://www.astro.uni-bonn.de/~webgk/dgeproc/dge111.ps.gz
dc.identifierhttps://arxiv.org/abs/astro-ph/0110040
dc.identifierhttp://arxiv.org/abs/astro-ph/0110040
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/3443
dc.subjectAstrophysics
dc.titleOptical & NIR Surface Photometry of I Zw 18
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