We observed the Class I protostellar source Elias 29 with the Atacama Large Millimeter/submillimeter Array. We detected CS, SO, 34SO, SO2, and SiO line emissions in a compact component concentrated near the protostar, and a ridge component separated from the protostar by 4″ (∼500 au). The former component is abundant in SO and SO2, but deficient in CS. The abundance ratio SO/CS is as high as at the protostar, which is even higher than that in the outflow-shocked region of L1157 B1. However, organic molecules (HCOOCH3, CH3OCH3, CCH, and c-C3H2) are deficient in Elias 29. We attribute this deficiency in organic molecules and richness in SO and SO2 to the evolved nature of the source or the relatively high dust temperature (⪆20 K) in the parent cloud of Elias 29. The SO and SO2 emissions trace rotation around the protostar. Assuming a highly inclined configuration (i ≥ 65°; 0° for a face-on configuration) and Keplerian motion for simplicity, the protostellar mass is estimated to be (0.8-1.0) . The 34SO and SO2 emissions are asymmetric in their spectra; the blueshifted components are weaker than the redshifted ones. Although this may be attributed to the asymmetric molecular distribution, other possibilities are also discussed.
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