Sulfur-Bearing Species Tracing the Disk/Envelope System in the Class I
  Protostellar Source Elias 29
  We have observed the Class I protostellar source Elias 29 with Atacama Large
Millimeter/submillimeter Array (ALMA). We have detected CS, SO, $^{34}$SO,
SO$_2$, and SiO line emissions in a compact component concentrated near the
protostar and a ridge component separated from the protostar by 4\arcsec\
($\sim 500$ au). The former component is found to be abundant in SO and SO$_2$
but deficient in CS. The abundance ratio SO/CS is as high as $3^{+13}_{-2}
\times 10^2$ at the protostar, which is even higher than that in the
outflow-shocked region of L1157 B1. However, organic molecules (HCOOCH$_3$,
CH$_3$OCH$_3$, CCH, and c-C$_3$H$_2$) are deficient in Elias 29. We attribute
the deficiency in organic molecules and richness in SO and SO$_2$ to the
evolved nature of the source or the relatively high dust temperature
(\protect\raisebox{-0.7ex}{$\:\stackrel{\textstyle >}{\sim}\:$} 20 K) in the
parent cloud of Elias 29. The SO and SO$_2$ emissions trace rotation around the
protostar. Assuming a highly inclined configuration ($i \geq 65$\degr; 0\degr\
for a face-on configuration) and Keplerian motion for simplicity, the
protostellar mass is estimated to be (0.8 -- 1.0) \Msun. The $^{34}$SO and
SO$_2$ emissions are asymmetric in their spectra; the blue-shifted components
are weaker than the red-shifted ones. Although this may be attributed to the
asymmetric molecular distribution, other possibilities are also discussed.
