When the flux of radiation from a star (or disk) is large enough, the radiative force exerted on the particles in the outer layers may exceed the weight of the particles. The point of balance is known as the Eddington limit and it has been assumed that stars cannot exist at masses greater than (about) the 100Msun at which this balance is reached. However, stars at larger masses have been detected and the question of how they manage is thereby raised. I will use some laboratory analogues to suggest that the atmospheres of hot massive stars make photon bubbles and that, because of the rapid rotation of these stars, the bubbles coalesce into vortices or magnetic flux tubes that are conduits for the escaping radiation. The discussion will be largely phenomenological.
Monday 23 March, from 10am to noon
IHP, Room 314
11, rue Pierre et Marie Curie
75005 Paris