The J = 2 - 1 and 3 - 2 rotational lines of the rare isotopomer C ^ { 36 } S and the J = 5 - 4 and 6 - 5 transitions of Si ^ { 36 } S were detected in the carbon star IRC+10216 ( CW Leo ) .
These are the first detections of ^ { 36 } S bearing molecules in a star and the first spectroscopic detection of Si ^ { 36 } S. From a comparison of ^ { 34 } S and ^ { 36 } S bearing isotopomers , the ^ { 34 } S/ ^ { 36 } S isotopic ratio is 107 ( \pm 15 ) .
This value is comparable to values in the interstellar medium of the inner Galactic disk ( 115 ) but is smaller than the solar value of 288 ( Ding et al . [ 2001 ] ) .
The increase of the ^ { 36 } S abundance relative to ^ { 34 } S only qualitatively follows model predictions of a low mass AGB star .
Quantitative agreement of the observed ^ { 34 } S/ ^ { 36 } S ratio with the stellar models can be reached if the age of IRC+10216 and Galactic chemical evolution are taken into account .
Other less likely possibilities are the presence of considerable inhomogeneities in the interstellar medium and either IRC+10216 or the Sun started with a peculiar ^ { 36 } S abundance .
Other production mechanisms potentially capable of enhancing the Galactic interstellar medium are discussed .
From the observed line density toward IRC+10216 and toward Galactic star forming regions , we estimate the confusion limit toward those sources .