Michael Burton (UNSW)

Michael Burton Colloquium -- The Mopra Southern Galactic Plane CO Survey - the formation of molecular clouds

Abstract

Stars form inside molecular clouds, almost as soon as the clouds themselves are formed. But how do molecular clouds form in the first place? They are thought to arise from the atomic substrate but this is a process that has not yet been witnessed, since the dominant forms of the gas (i.e. H or H2) do not show clear diagnostics of the formation process. This must be followed through trace species, in particular carbon, as it transitions from ionized, through neutral and into molecular form (i.e. CO). Furthermore, some parts of molecular clouds may themselves may be "dark", that is be essentially pure H2 (without CO). Telescopes that can survey the Galactic plane for the emission lines of the diagnostic tracers (C+, C, CO) are required to make progress on this problem; i.e. THz – mm-wave telescopes. In this talk we will outline the problem of molecular cloud formation and describe a program aimed at tackling it, using a suite of telescopes – in Australia, Chile and Antarctica. In particular, we will discuss the first results from a survey underway with the 22m Mopra millimetre-wave telescope, to survey the southern Galactic plane in the fundamental isotopologues of the CO molecule.