Talk Details

Monday, November 10, 2014 - 11:00am

Jorge Abreu-Vicente (MPIA):

"Relationship between density structure and evolutionary class of molecular clouds"

Abstract. We perform the first Galactic scale study of the relationship between the column density (N(H2)) as traced by dust emission and their evolutionary status as measured by their stellar content. We analyze a sample of 195 molecular clouds located at distances < 5.5 kpc, identified from the ATLASGAL 870 μm data. We define three evolutionary classes within this sample: starless clumps (SLCs), protostellar clouds (PSCs), and Hii regions. We find a strong dependence between the N(H) probability density function (N-PDFs) shape and the evolutionary class of a molecular cloud: the N-PDFs of SLCs are log-normal functions while PSCs and Hii regions exhibit log-normal components at low N(H) values and power-law components at high N(H) values. The N-PDFs suggest evolutionary time-scales of ∼0.1Myr for SLCs, ∼0.3Myr for PSCs, and ∼0.7Myr for Hii regions. Finally, we show that the integral of the N-PDFs, the dense gas mass fraction, depends on the total mass of the regions as measured by ATLASGAL: more massive clouds contain greater relative amounts of dense gas across all evolutionary classes.