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Description
Two mid-infrared quiet and two brighter massive cores were observed in various transitions (E_up_ up to 289K) of CS, OCS, H_2_S, SO, and SO_2_ and of their ^34^S isotopologues at mm wavelengths with the IRAM 30m and CSO telescopes. The 1D modeling of the dust continuum is used to derive the density and temperature laws, which were then applied in the RATRAN code to modeling the observed line emission and to deriving the relative abundances of the molecules. All lines are detected, except the highest energy SO_2_ transition. Infall (up to 2.9km/s) may be detected towards the core W43MM1. We propose an evolutionary sequence of our sources (W43MM1 - IRAS18264-1152 - IRAS05358+3543 - IRAS18162-2048), based on the SED analysis. The analysis of the variations in abundance ratios from source to source reveals that the SO and SO_2_ relative abundances increase with time, while CS and OCS decrease. Molecular ratios, such as [OCS/H_2_S], [CS/H_2_S], [SO/OCS], [SO_2_/OCS], [CS/SO], and [SO_2_/SO] may be good indicators of evolution, depending on layers probed by the observed molecular transitions. Observations of molecular emission from warmer layers, so that involving higher upper energy levels must be included.
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