Orion B cores maps physical properties

The main properties of the core sample are derived using the Principal Component Analysis and additional maps of physical parameters: column density N_H2_, far-ultraviolet (FUV) radiation field G0 and mean volume gas density n. Additional high spectral resolution observations of C^18^O(1-0) serve to evaluate the dynamical status of cores. The average line width of the cores is larger than what is typically expected for prestellar cores of closer star forming regions, which suggests that cores in Orion B are subjected to stronger turbulence affecting their stability.

The first factor of the PCA analysis explaining the variation of the detected line intensities is the core column density of molecular gas. The second factor explains how the core chemical composition is strictly linked to their environment, which can be traced by the ratio of the external FUV radiation field over the core volume density, G0/n. Cold and shielded cores exhibit strong emission of N_2_H^+^, CH_3_OH and deuterated species, whereas cores exposed to radiation are devoid of typical core tracers, but exhibit emission of ^12^CN, HCO^+^ and HCN.

The third factor explaining the core chemical diversity is the mean density along the core line of sight, which is also associated with freeze-out and fractionation signatures. Pre-stellar cores selected based on their dust emission exhibit a wide range of line emission patterns, which can be related to their intrinsic properties (column density N_H2_, mean volume density n) and environment (presence or lack of FUV). The key parameter that distinguishes cores of different emission patterns is G0/n.