Astron. Astrophys. Suppl. Ser. 139, 231-244

A UKST survey of blue objects towards the galactic centre
- a search for early-type stars

P.L. Dufton¹ - S.J. Smartt² - N.C. Hambly^3,4

Send offprint request: sjst@ing.iac.es

1 - The Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, N. Ireland
2 - Isaac Newton Group of Telescopes, Apartado de Correos 368, E-38700, Santa Cruz de La Palma
3 - Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, Scotland, UK
4 - Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, Scotland, UK

Received April 21; accepted June 30, 1999

Abstract:

We have begun a search for early-type stars towards the galactic centre which are potentially young objects situated within the inner few kiloparsecs of the disk. U and V (or I) band photographic photometry from the UK Schmidt Telescope has been obtained to identify the bluest candidates in nineteen Schmidt fields (centred close to the galactic centre). We have spectroscopically observed these targets for three fields with the FLAIR multi-fibre system to determine their spectral types. In particular, ten early B-type stars have been identified and equivalent width measurements of their Balmer and HeI lines have been used to estimate atmospheric parameters. These early-type objects have magnitudes in the range $11.5\leq V\leq 16.0$, and our best estimates of their distance (given probable highly variable reddening in this direction together with errors in the plate photometry) suggest that some of them originated close to (i.e $R_{\rm g}<3$ kpc), or even beyond the galactic centre. Future high-resolution spectroscopy of these stars will provide reliable atmospheric parameters and element abundances, in order to map the current chemical composition of the inner galaxy.

Key words: stars: early-type -- stars: fundamental parameters -- stars: imaging -- galaxy: center