Silicon sulfide, SiS, has been recently detected in a shocked region around a Sun-like protostar (L1157-B1) with an anomalously high abundance with respect to the more common SiO. This has challenged our comprehension of silicon chemistry in the interstellar medium. In this paper, the reaction H+SiS2 has been computationally investigated by means of electronic structure and kinetic calculations to establish its role in the conversion of interstellar SiS2 into SiS by the abundant H atoms. The calculated reaction rate coefficients between 70–100 K are high enough to conclude that SiS2 cannot be considered a reservoir species of silicon or sulphur in interstellar objects and that, if formed, SiS2 is rapidly converted into SiS+HS by the reaction with atomic hydrogen.
A theoretical investigation of the reaction H+SIS2and Implications for the Chemistry of Silicon in the Interstellar Medium
Rosi, Marzio;Balucani, Nadia;Mancini, Luca;Lago, Noelia Faginas;
2018
Abstract
Silicon sulfide, SiS, has been recently detected in a shocked region around a Sun-like protostar (L1157-B1) with an anomalously high abundance with respect to the more common SiO. This has challenged our comprehension of silicon chemistry in the interstellar medium. In this paper, the reaction H+SiS2 has been computationally investigated by means of electronic structure and kinetic calculations to establish its role in the conversion of interstellar SiS2 into SiS by the abundant H atoms. The calculated reaction rate coefficients between 70–100 K are high enough to conclude that SiS2 cannot be considered a reservoir species of silicon or sulphur in interstellar objects and that, if formed, SiS2 is rapidly converted into SiS+HS by the reaction with atomic hydrogen.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
