Chemistry of TMC-1 with multiply deuterated species and spin chemistry of H ₂ , H ₂ ⁺ , H ₃ ⁺ and their isotopologues

Abstract

Deuterated species are unique and powerful tools in astronomy since they can\nprobe the physical conditions, chemistry, and ionization level of various\nastrophysical media. Recent observations of several deuterated species along\nwith some of their spin isomeric forms have rekindled the interest for more\naccurate studies on deuterium fractionation. This paper presents the first\npublicly available chemical network of multiply deuterated species along with\nspin chemistry implemented on the latest state-of-the-art gas-grain chemical\ncode `NAUTILUS'. D/H ratios for all deuterated species observed at different\npositions of TMC-1 are compared with the results of our model, which considers\nmultiply deuterated species along with the spin chemistry of light hydrogen\nbearing species H2, H2+, H3+ and their isotopologues. We also show the\ndifferences in the modeled abundances of non-deuterated species after the\ninclusion of deuteration and spin chemistry in the model. Finally, we present a\nlist of potentially observable deuterated species in TMC-1 awaiting detection.\n