Galactic abundance gradients from ob-type stars in young clusters and associations
High-resolution spectra of main sequence B-type stars in young galactic clusters have been analysed using LTE and (where appropriate) non-LTE model atmosphere calculations. A re-analysis of the O II data from 11 clusters indicates that within 2 kpc of the sun there appears to be no obvious abundance gradient with respect to galactocentric distance. However, the cluster Dolidze 25 lying at R g = 13.5 kpc has been found to be oxygen deficient, implying that the abundance gradient may be non-linear. A comparison with studies of H II regions indicates that within the uncertainties the two methods yield consistent abundances. We are currently analysing clusters with 10 kpc ≤ Ry ≤ 12kpc and will shortly be obtaining data on clusters with R g ≤ 16kpc.
KeywordsSolar Neighbourhood Oxygen Abundance Galactocentric Distance Young Cluster Abundance Gradient
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