AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 71. Between the Stars II: The ISM, Galactic and Extragalactic
Display, Wednesday, June 2, 1999, 10:00am-6:30pm, Southwest Exhibit Hall

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[71.05] HST Imagery of the Dusty SMC H~{\sc ii} Region Henize 88A

R.J. Dufour (Rice U.), C.M. Kurt (United Space Alliance)

Henize 88A is a small H~{\sc ii} region in the eastern ``Shapley Wing'' of the Small Magellanic Cloud noted to be unusual compared to other SMC H~{\sc ii} regions because of large amounts of dust associated with the ionized gas. It's UV-optical spectra were recently studied in detail with HST FOS and its morphology in H\alpha and [O~{\sc iii}] 5007 Å~with WFPC1 by Kurt et. al. (1999, ApJ, in press). They found evidence for the ionized gas to be enriched in C and Si relative to other SMC H~{\sc ii} regions and concluded that SMC N88A is a very young H~{\sc ii} region forming out of a small dusty molecular cloud which is being disrupted by star formation of one or more massive stars.

In this poster we report on the results of new and extensive HST WFPC2 observations of SMC N88A obtained in 1998 November. Images were taken through filters isolating the emission lines of [O{\sc ii}] 3727 Å, H\beta, [O~{\sc iii}] 5007 Å, H\alpha, [S~{\sc ii}] 6717+31 Å, and [S~{\sc iii}] 9532 Å. Continuum observations were made through the F336W (``U'') and F547M (``narrow-V'') filters. These data were combined, processed, and calibrated to produce 0\farcs1 resolution contour and color-coded maps of the nebula of its (a) line of sight extinction; (b) ionization structure in H+, O+, O+2, S+, and S+2; (c) density structure of the ionized gas; (d) the distribution of dust in and around the nebula; and (e) a three-dimensional model of the nebula and its surrounding dust. The photoionization code CLOUDY is used to model the ionization structure of the nebula based on the above maps and used to re-evaluate physical conditions and abundances presented in the Kurt et al. (1999) study. Finally, we compare the properties of N88A to another similar, but relatively dust-free, SMC H~{\sc ii} region, N81, for which similar HST WFPC2 observations have recently become available.

The color-coded imagery and some of the results of our modeling will be available on the WWW at http://regultra.rice.edu/smcn88a.html beginning just prior to the meeting (30 June 1999). This study was supported in part by AURA/STScI grant GO-06839.01-95A to Rice University.

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