the Program for New Century Excellent Talents in University of China (Grant No. NCET-05-0144);the Doctoral Fund of Ministry of Education of China (Grant No. 20060027013);the National Natural Science Foundation of China (Grant No. 10473003)
The circumstellar envelope of evolved stars of low- and intermediate-mass is an important site for dust formation. In comparison with the interstellar medium, they have more types of organics and different types of in...