The chemical composition towards the Galactic anti-centre. I. Observations and model atmosphere analyses

The Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, N. Ireland

Send offprint request to: S.J. Smartt

Received: 24 July 1995
Accepted: 14 October 1995

Abstract

High resolution spectra of six early B-type main-sequence stars having galactocentric distances of between 10 and 18 kpc are presented. We list the equivalent widths for the metal lines and illustrate their hydrogen and helium line profiles. The stars are analysed using LTE line-blanketed model atmosphere techniques to derive atmospheric parameters and surface chemical compositions. All six stars have similar effective temperatures and surface gravities, allowing a reliable comparison of their metal abundances and distances. Significant variations in the photospheric abundances are evident and we discuss the need for a more detailed line-by-line differential analysis to exactly quantify the differences. This will be presented in a companion paper (Smartt et al. 1996).