Contents of: VI/111/./abstract/PDUFTON_PROP_190.abs

The following document lists the file abstract/PDUFTON_PROP_190.abs from catalogue VI/111.
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 From model atmosphere analyses of the spectra of B-type stars in
 young clusters, we have found zero galactic abundance gradients
 for the solar neighbourhood (i.e. within 3 kpc of the sun).  At
 larger galactocentic distances, we find considerable abundance
 variations over relatively small distance scales (i.e.  1 kpc).
 These results are significantly different from those deduced from
 H II region observations. However our discussion of these
 discrepancies has been compromised by the lack of data for both
 the B-type stars and their associated H II regions. We therefore
 plan to observe with ISO the H II regions directly associated with
 early-type stars that we have previously analysed viz. S 208, S 212
 and S 285 for a spring and the first two only for an autumn launch.
 The ISO observations will be supplemented with our existing optical
 data for the H II regions plus new observations, which will be
 obtained using time recently awarded to us on the 4.2 m William
 Herschel Telescope. The nebular abundances will be compared with
 the B-type stellar values, which will allow us to investigate if
 the discrepancies discussed above are due to: (a) errors in
 (probably) the H II region analyses, (b) variations in their dust
 content, and/or (c) the stellar observations identifying abundance
 variations on a small spatial scale beyond those seen in the H II
 region results. As H II regions are used extensively to map
 abundances in external galaxies, it is important that these
 discrepancies are understood.

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