Previous abstract Next abstract
Session 108 - HII Regions.
Display session, Thursday, January 18
North Banquet Hall, Convention Center
As part of the HST General Observer Program GO-6042, parallel WFPC2 images of locations in the large Carina H \sc ii region were taken during a series of FOS spectra of several ejecta of Eta Carinae (cf., the poster by Glover et al. at this meeting). The observations were scheduled during two CVZ (continuous viewing zone) visits in 1995 October, enabling deep WFPC2 exposures to be taken in ten filters. The ``serendipitous'' target was an area which included the Cr 232 star cluster and surrounding H \sc ii region, about 8 arcmin to the NW of Eta Carinae itself. Images of the nebula were obtained in the filters F656N (H\alpha), F673N ([S \sc ii] 6717+31 ÅF658N ([N \sc ii] 6583 ÅF502N ([O \sc iii] 5007 Åand F547M (continuum) for puposes of studying the ionization structure. In addition, relatively long (\sim1000 sec) exposures were obtained though the wide-band filters F336W, F439W, and F555W for purposes of obtaining UBV magnitudes and colors of stars down to a limiting magnitude of V\sim25.
We present the results of this imagery in the form of (a) color-coded emission line ratio maps of the nebulosity in the various lines noted above, and (b) color-magnitude (CMD) and color-color diagrams of faint stars in the field. At a distance of 2500 pc for the nebula and cluster, the spatial resolution of 0.1 arcsec on the WFPC2 imagery corresponds to 250 AU per pixel, a scale that resolves numerous Bok globules not previously seen from ground-based imagery. These globules are seen in absorption in the [O \sc iii] images and with bright rims in [S \sc ii] and [N \sc ii], indicating their proximity to the cluster OB stars and location in the ionized volume of the nebula. Our CMDs, (very preliminary at the time of writing) reach M_V\sim+11 for stars at the distance of the Cr 232 cluster. A prominent reflection nebula is also seen around one of the stars in the cluster.
This study is made possible by grants from AURA/STScI related to GO-6042 and the HST Cycle 5 TAC, which supported our expectations regarding science that would result from the parallel imagery.
Program listing for Thursday