Lucy A. Wilcock

 

IRDCs seen in the HiGAL survey - structures, statistics and evolution

D. Ward-Thompson, J.M. Kirk, D. Stamatellos, A. Whitworth, C. Battersby, C. Brunt, G.A. Fuller, M. Griffin, S. Molinari, P. Martin, J.C. Mottram, N. Peretto, R. Plume, H.A. Smith, M.A. Thompson

 

We have observed more than 3000 infrared dark cloud (IRDC) candidates in the Hi-GAL survey fields in the range l=300−330. We find that, of these, only around 1200 are genuine IRDCs and just under a thousand of these IRDCs contain one or more infrared dark cores that are visible in emission at 250 microns. Based on the statistics of those cores that contain sources at 8, 24 and 70 microns respectively, we are able to postulate an evolutionary sequence, with associated timescales, for cores within IRDCs. Furthermore, we present a detailed study of the structure of the least evolved and most isolated cores. We model their appearance at every wavelength, using a Monte Carlo code, to determine their physical parameters. We discuss the relationships between the mass, density, temperature, size, and surrounding interstellar radiation field of the cores.