EPoS Contribution
EPoS Contribution
Molecular inventory of the Infrared Dark Clouds

Tatiana Vasyunina
Max-Planck-Institut für Astronomie, Heidelberg, Germany
We present our latest results on dense gas properties in a new sample of southern infrared dark clouds (IRDCs), a class of objects commonly associated with the first stages of high-mass star formation. For this investigation molecular line observations with two Australian telescopes, Mopra and Parkes, have been performed. Line data give us important information about kinematic characteristics of our clouds, their distances, temperatures, and chemistry. From ammonia observations with the Parkes telescope we derived kinetic temperatures for our IRDCs between 10 and 20 K. This shows that even in the case of embedded 24 micron sources, the gas is not warmed up yet over large volumes. Temperature information let us calculate more realistic clouds masses and column densities. Analysis of the Mopra 3mm data (86-93 GHz) shows the chemical variety and complexity of IRDCs. We did not detect any evidence of a hot-core chemistry even in the most evolved regions in our sample. However, the presence of SiO emission in some clouds and complicated shapes of the HCO+ emission line in all IRDCs indicate the presence of outflows, in some cases infall motions, and the beginning of star formation activity. Clear and good detection of N2H+, HNC, HCO+ and HCN lines, in combination with our millimeter continuum data, let us calculate their abundances. Using chemical network modeling we determine the evolutionary status of our IRDCs.
Collaborators:
H. Linz, MPIA, Germany
Th. Henning, MPIA, Germany
H. Beuther, MPIA, Germany
I. Zinchenko,IAP, RAS, Russia
M. Voronkov,ATNF, CSIRO, Australia
Key publication

Suggested Session: Massive Stars