THE BIRTH OF A PLANETARY-NEBULA AROUND THE CARBON STAR IRC+10216

Our current understanding of the evolution of solar-type stars suggest s that after a period as a red giant star, during which mass loss occu rs continuously in the form of a stellar wind, a period of intense mas s loss known as a superwind occurs, during which a significant fractio n of the envelope of the star is ejected into space, forming the mater ial from which a planetary nebula (PN) will be constructed. It has bee n suggested that this superwind ejects material from the star in a tor oidal or disc-like fashion, rather than isotropically. Here we present Hubble Space Telescope optical images of a toroidal superwind caught in the act: our images of the carbon star IRC+10216, which is believed to be in the final stages of red giant evolution, show that most of i ts optical emission is a bipolar reflection nebula. We show that the f ull spectral energy distribution and these images can be modelled as a n equatorially enhanced dusty superwind, providing the first direct ob servational support for the toroidal superwind model, and supporting t he 'interacting winds' model of PN formation.