000001963 001__ 1963
000001963 005__ 20160701171656.0
000001963 0247_ $$2DOI$$a10.1051/0004-6361:20034480
000001963 037__ $$aASTROimport-120
000001963 100__ $$aVan Loo, S.
000001963 245__ $$aNon-thermal radio emission from single hot stars
000001963 260__ $$c2004
000001963 520__ $$aWe present a theoretical model for the non-thermal radio emission from single hot stars, in terms of synchrotron radiation from electrons accelerated in wind-embedded shocks. The model is described by five independent parameters each with a straightforward physical interpretation. Applying the model to a high-quality observation of Cyg OB2 No. 9 (O5 If), we obtain meaningful constraints on most parameters. The most important result is that the outer boundary of the synchrotron emission region must lie between 500 and 2200 stellar radii. This means that shocks must persist up to that distance. We also find that relatively weak shocks (with a compression ratio 3) are needed to produce the observed radio spectrum. These results are compatible with current hydrodynamical predictions. Most of our models also show a relativistic electron fraction that increases outwards. This points to an increasing efficiency of the acceleration mechanism, perhaps due to multiple acceleration, or an increase in the strength of the shocks. Implications of our results for non-thermal X-ray emission are discussed. 
000001963 700__ $$a Runacres, M. C.
000001963 700__ $$a Blomme, R.
000001963 773__ $$c717-725$$pAstronomy and Astrophysics$$v418$$y2004
000001963 85642 $$ahttp://esoads.eso.org/abs/2004A%26A...418..717V
000001963 905__ $$apublished in
000001963 980__ $$aREFERD