Relation between HDS/H₂S (top row), D₂S/H₂S (middle row), and D₂S/HDS (bottom row) abundance ratios and starless cores’ physical parameters: kinetic temperature (left), extinction (middle), and molecular hydrogen density (right). The dataset is colour-coded in each row according to the way of estimation of H₂S column density, as indicated in the legends. Different symbols indicate the molecular cloud of the points, as indicated in the legend of the first panel. Filled symbols correspond to direct detections of HDS (top row) or D₂S (middle row), and open symbols correspond to the upper limits, respectively. In the case of D₂S/HDS (bottom row), filled symbols indicate direct detection of both HDS and D₂S, and open symbols indicate the direct detection of HDS and the upper limits of D₂S.