Bulletin de la Société Royale des Sciences de Liège Bulletin de la Société Royale des Sciences de Liège -  Volume 80 - Année 2011 

Radio observations of massive stars

Ronny Blomme

Royal Observatory of Belgium, Ringlaan 3, B-1180 Brussel, Belgium

Abstract

Detectable radio emission occurs during almost all phases of massive star evolution. I will concentrate on the thermal and non-thermal continuum emission from early-type stars. The thermal radio emission is due to free-free interactions in the ionized stellar wind material. Early ideas that this would lead to an easy and straightforward way of measuring the mass-loss rates were thwarted by the presence of clumping in the stellar wind. Multi-wavelength observations provide important constraints on this clumping, but do not allow its full determination. Non-thermal radio emission is associated with binarity. This conclusion was already known for some time for Wolf-Rayet stars and in recent years it has become clear that it is also true for O-type stars. In a massive star binary, the two stellar winds collide and around the shocks a fraction of the electrons are accelerated to relativistic speeds. Spiralling in the magnetic field these electrons emit synchrotron radiation, which we detect as non-thermal radio emission. The many parameters that influence the resulting non-thermal radio fluxes make the modelling of these systems particularly challenging, but their study will provide interesting new insight into massive stars.

Pour citer cet article

Ronny Blomme, «Radio observations of massive stars», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 80 - Année 2011, 67 - 80 URL : http://popups.ulg.be/0037-9565/index.php?id=2541.