Cs Line Profiles in Hot Cores

We present a theoretical study of CS line profiles in archetypal hot cores. We provide estimates of line fluxes from the CS(1–0) to the CS(15–14) transitions and present the temporal variation of these fluxes. We find that (1) the CS(1–0) transition is a better tracer of the Envelope of the hot core whereas the higher- J CS lines trace the ultracompact core (UCC); (2) the peak temperature of the CS transitions is a good indicator of the temperature inside the hot core; (3) in the Envelope, the older the hot core the stronger the self-absorption of CS; (4) the fractional abundance of CS is highest in the innermost parts of the UCC, confirming the CS molecule as one of the best tracers of very dense gas.