EDP Sciences
Free access
Issue
A&A
Volume 373, Number 2, July II 2001
Page(s) 608 - 624
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20010613


A&A 373, 608-624 (2001)
DOI: 10.1051/0004-6361:20010613

A UKST survey of blue objects towards the Galactic centre - seven additional fields

P. L. Dufton1, S. J. Smartt2 and N. C. Hambly3

1  The Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast BT7 1NN, N. Ireland, UK
2  Institute for Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0BA, UK
3  Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, Scotland, UK

(Received 2 April 2001 / Accepted 27 April 2001 )

Abstract
We are searching for early-type stars towards the Galactic centre which are potentially young objects situated within the inner few kiloparsecs of the disk. Photographic photometry from the UK Schmidt Telescope has been used to identify the bluest candidates in nineteen Schmidt fields (centred close to the Galactic centre). We have previously obtained FLAIR low dispersion spectroscopy for three of these fields to estimate spectral types and here we present spectroscopy for an additional seven fields. Combining the results for all ten fields, 56 stars were initially classified as early-B type. Estimates of the equivalent widths of their Balmer and He I lines have been used to estimate atmospheric parameters and 32 targets have effective temperatures greater than or equal to 17 000 K (corresponding to a spectral type of B3 or earlier). The spectra of seven of these targets also have absorption lines due to OII and SiIII and can be reliably classified as early-B type. Additionally 78 stars have estimated effective temperatures between 11 000 and 16 000 K with a further a further 50 objects identified as late-B (or early-A) type. All but two of the early B-type candidates have magnitudes in the range $12.0\leq V\leq 16.0$, and our best estimates of their distance suggest that they could be close to (i.e. $R_{\rm g}< 3$ kpc), or even beyond the Galactic centre.


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

Offprint request: P. L. Dufton, p.dufton@qub.ac.uk

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