RSAA Colloquia / Seminars / Feast-of-Facts: Friday, 17 November 2017, 14:00-14:20; Duffield Lecture Theatre

Adam Onus

"Calibrating the Relation Between HCN Luminosity and Star Formation Rate in Molecular Clouds"

Stars form in dense gas. The molecular emission line HCN(1-0) is thought to be a tracer of dense gas, with strong emissivity typically observed in regions of active star formation. For the past dozen years, work by the likes of Gao & Solomon (2004), Wu et al. (2005,2010), Usero et al. (2015), Bigiel et al. (2015,2016) and more have gone a long way towards defining how star formation rates and HCN emission luminosities relate. The observed correlation offers strong constraints on the efficiency of star formation in dense gas, but to make this precise we need to calibrate the mapping between HCN emission and gas mass and density. In this talk I will discuss my research with Christoph and Mark on calibrating such a correlation through post-processing of high-resolution simulations of star formation in dense gas clouds. Our work confirms existing correlations between HCN luminosities and dense gas; and we present a new empirical relationship between HCN emission and star formation rates that calibrates the observed values to yield physical star formation rates per freefall time.