Abstract
In this thesis, we investigated the HC3N (J＝5-4) emission at 45490.3 MHz from the circumstellar envelopes of five carbon rich stars (LP And, V Cyg, IRAS 22272＋5435, V384 Per, RAFGL 2155). The observations were carried out using the Very Large Array of the National Radio Astronomical Observatory. The high angular resolution of ∼1”.5 allows us to resolve the distribution of HC3N in these envelopes into hollow shell structure in constant expansion. Such distribution is in broad agreement with prediction of chemical models on the formation of HC3N molecules. We also find that the distribution of HC3N is clumpy and in a few cases asymmetric. Interestingly, we find a clear relation between mass loss rate from the central star and the linear size of the envelope. Our results provide very useful constraints to the current chemical models for the carbon rich envelope.