Fig. 5.

Schematic diagram of the solar nebula (0.1–100 AU), irradiated by stellar and interstellar UVs and X-rays (height of the disk is scaled by the radius, i.e., Z/R). White lines represent electron fraction isolines. Both the electron fractions and the gas temperature scale are adapted from ref. 53. Synthesis of ¹⁵N- and noble gas-rich organics is possible in the most ionized areas of the disk, via photon and/or electron–gas interactions. The source of ¹⁵N enrichment is the UV photodissociation of N₂ in the PDR region only. Dispersion of organics within the disk is possible thanks to turbulence and settlement. Organics may interact with ices in the cold and shielded middle part of the disk.