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″ ( \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 ( \ > \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 ° ; 0° for a face-on configuration ) and Keplerian motion for simplicity , the protostellar mass is estimated to be ( 0.8 – 1.0 ) M _ { \odot } .
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 .