Schematic representation of the IRS 44 system. Infalling streamers produce accretion shocks in the outer regions of the rotating-infalling envelope and a Keplerian disk is expected in the innermost regions of IRS 44 B. Most of the C is locked into CO; thus, CS and H₂CS formation is not efficient. Accretion shocks sublimate S-bearing species and enhance their gas abundances, promoting a lukewarm chemistry (~200 K) in the gas phase, mainly involving O- and S-bearing species.