The Evolutionary History of the R Coronae Borealis Stars
Geoffrey Clayton
Louisiana State University

The R Coronae Borealis (RCB) stars are very rare and very exciting. Their rarity may stem from the fact that they are in an extremely rapid phase of the evolution or in an evolutionary phase that most stars do not undergo. The universe and almost all of the stars in it are about 90% hydrogen. The RCB stars have almost no hydrogen. They also have some very strange isotopic abundances. In particular, they have about as much oxygen-18 as oxygen-16 whereas normal stars like our Sun have 500 times as much oxygen-16 as oxygen-18. The RCB stars are best known for suddenly, in a few weeks or months, becoming thousands of times fainter than normal. This is caused by the formation of clouds of carbon dust which eclipse the star. It is possible that the bizarre nature of these stars can be explained if they are the product of two stars which have merged into one star. I will present recent visible and Infrared observations of various RCB stars obtained with Hubble Space Telescope, and other space- and ground-based telescopes. I will also present the results of hydrodynamic simulations of stellar mergers which we hope will produce RCB stars.

Date:	Jeudi, le 6 février 2014
Heure:	11:30
Lieu:	Université de Montréal
	Pavillon Roger-Gaudry, local D-460
Contact:	Patrick Dufour