¹ Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD, UK
² Bartol Research Institute, University of Delaware, Newark, DE 19711, USA
³ Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK

Recent observations of blue stragglers by De Marco et al. (2004) have revealed continuum deficits on the blue side of the Balmer discontinuity, leading these authors to infer the presence of discs around the stars. This intriguing possibility may throw light on aspects of the mechanisms responsible for at least some of these objects; current theories of blue straggler formation invoke stellar collisions or interacting binaries, both of which appear capable of forming a circumstellar disc.

However, by synthesizing photospheric spectra for models of rotating blue stragglers, we demonstrate that the Balmer jump enhancements can be wholly attributed to the influence of oblateness and gravity darkening on the formation of the continuum. Therefore, we are led to conclude that the observations of De Marco et al. can be ascribed a more prosaic explanation, that of rapid stellar rotation arising from the merger/interaction formation process.

Accepted by ApJL
Preprints from jmp@astro.livjm.ac.uk
Or on the web at http://arxiv.org/abs/astro-ph/0503437