Speaker
Katharine Johnston
(MPIA, Heidelberg)
Description
The massive infrared dark cloud G0.253+0.016 projected 45pc from the Galactic centre contains 10^5 Msun of dense gas whilst being mostly devoid of observed star formation tracers. To scrutinise the gas properties of G0.253+0.016, we have carried out a concerted SMA and IRAM 30m study of this enigmatic cloud in dust continuum, CO isotopologues as low-density tracers, as well as CH3OH and SiO as shock tracers. In this talk, I will firstly discuss in detail the density structure of the cloud traced by column density PDFs and dendrograms, with relation to whether star formation is currently ongoing. I will then show how our observations suggest that G0.253+0.016 is colliding with another cloud - in fact, this may have been the formation scenario for G0.253+0.016. The collision will also likely affect its structure, internal turbulence, and final star-forming fate. I will finally discuss how G0.253+0.016 fits into our picture of the dynamics and geometry of the Galactic centre region. Specifically, I will show that the model of the 100pc Galactic centre ring put forward by Molinari et al. (2011) does not explain the observed longitude-velocity diagrams of the CMZ observed by Jones et al. (2012), and thus a different orientation and/or geometry is required.
Author
Katharine Johnston
(MPIA, Heidelberg)