Wednesday 12 Nov 2014: Seminar: The dynamics and star-forming potential of the massive Galactic Centre cloud G0.253+0.016
Dr Katharine Johnston - University of Leeds
Physics, 4th floor 14:00-15:00
It is unclear whether star formation proceeds in a similar manner in the Central Molecular Zone of our Galaxy to that observed in nearby clouds. In this talk, I will give an overview of the results of our recent study of the massive Galactic Centre infrared dark cloud G0.253+0.016 (aka 'the Brick'). Projected 45 pc from the Galactic Centre, G0.253+0.016 contains ~10^5 Msun of dense gas whilst being mostly devoid of observed star-formation tracers. To scrutinise the physical properties, dynamics and structure of this cloud with reference to its star-forming potential, we carried out a concerted SMA and IRAM 30 m study in dust continuum and molecular gas tracers. We find shock tracers, broad linewidths, and several overlapping velocity components towards the south of the cloud, indicating that G0.253+0.016 is colliding with another cloud at ~70 km/s. Despite the high mass and density of the cloud, we also find that its column density PDF and delta-variance spectrum are consistent with no or little current star-formation. Further, we find that the absolute column density threshold for nearby clouds modified for Galactic Centre turbulence is not sufficient to explain the lack of massive stars in G0.253+0.016, indicating that further physical effects such as magnetic fields may be important.