Isolated starless cores in infrared dark clouds in the Hi-GAL survey

In a previous paper, we identified cores within infrared dark clouds. We regarded those without embedded sources as the least evolved and labelled them starless. Here we identify the most isolated starless cores and model them using a three-dimensional multiwavelength Monte Carlo radiative transfer code. We derive the cores' physical parameters and discuss the relation between the mass, temperature, density, size and the surrounding interstellar radiation field (ISRF) for the cores. The masses of the cores were found not to correlate with their radial size or central density. The temperature at the surface of a core was seen to depend almost entirely on the level of the ISRF surrounding the core. No correlation was found between the temperature at the centre of a core and its local ISRF. This was seen to depend, instead, on the density and mass of the core.