Department of Physics, Engineering Physics & Astronomy

Department of Physics, Engineering Physics & Astronomy
Department of Physics, Engineering Physics & Astronomy

Between Dwarf Stars and Giant Planets: A Cosmic Identity Crisis

Ray Jayawardhana
University of Toronto

Wednesday, March 12, 2008
3:40 PM @ Stirling A

Abstract:

The past decade has witnessed dramatic progress in the study of extra-solar planets and brown dwarfs, objects that straddle the boundary between stars and planets. Astronomers often lump brown dwarfs and gas giant planets together as 'sub-stellar objects' because they share many physical characteristics. However, there are important differences as well: for example, most brown dwarfs are free-floating, though a few do orbit stars. Interestingly, recent surveys have revealed a number of planetary-mass objects --just a few times more massive than Jupiter-- also in isolation, blurring the identities further. With the detection of hundreds of brown dwarfs, both in the solar neighborhood and in young star clusters, the question of their origin has come to the forefront. Do they form in situ, from the collapse of puny cloud cores, or are they stellar embryos ejected from nascent stellar systems before they could grow into full-fledged stars? I will present observations of young brown dwarfs that may help distinguish among different scenarios for their formation, and discuss the intriguing possibility of planets circling objects that are not much heftier than themselves.