MSI Weekly Bulletin - Week starting Monday 21 May, 2007

Extragalactic jets are the turbulent result from one of the most powerful engines in the universe. They have been studied extensively at many different wavelengths - albeit passively. The availability of fast computers with large amounts of memory has opened the door to a revolutionary new field of astrophysics, where supercomputers running fluid simulations are being used to investigate the properties of extragalactic jets directly. The majority of simulations conducted thus far have used uniform meshes; which ultimately limits the dynamical range and size of the computational domain. In the last twenty years a powerful new form of fluid solver has been developed where the computational mesh is adaptively refined only where it is needed, thus increasing the size and dynamical range of the computational domain. The purpose of my honours project was to test one of these next-generation fluid codes in preparation for use by the high energy astrophysics group at the Research School of Astronomy and Astrophysics. In this talk I will be presenting some of the results from my project.

Beginning only in November 1995, astronomers have discovered a whole new world of substellar objects outside our solar system. These are now divided into two broad groups: (1) Planets around stars similar to our Sun -- but so far nearly all are similar to the mass and size of Jupiter, Earth-sized planets have not yet been reached (2) Brown Dwarfs -- objects more massive than Jovian planets, but not massive enough to fuse hydrogen to helium to produce luminous energy (the definition of a star) Complications: The great majority of brown dwarfs appear to have formed independently of any star. But what if a brown dwarf orbits a star -- is it not a planet? And what if a Jupiter-like object exists by itself in space? Is it a brown dwarf? This talk will summarize some properties of the atmospheres, interiors and statistics of these objects.