| Popis: |
Gas phase Elemental abundances in Molecular CloudS (GEMS) is an IRAM 30m Large Program aimed at determining the elemental abundances of carbon (C), oxygen (O), nitrogen (N), and sulphur (S) in a selected set of prototypical star forming filaments. Elemental abundances have a key role in the star formation process by driving the gas cooling rate and the gas ionization degree. Defining elemental abundance as the amount of a given atom in volatiles, the elemental abundances of C, O, and N in the interstellar medium are currently known within a factor of a few. However, the elemental abundance of S remains uncertain by several orders of magnitude, and its determination is one of the most challenging goals of this program. This is a review of the observational, theoretical, and modeling effort that GEMS team is doing to improve our knowledge of the sulphur chemistry. Our results suggest that the sulphur elemental abundance depends on the local physical conditions and the star formation activity in the environment. |
