We have a number of programs on the ISO satellite to study the chemical synthesis of complex molecules in the circumstellar environment. By comparing the infrared spectra of proto-planetary nebulae and planetary nebulae, we found that the circumstellar material changes from an aliphatic to aromatic structure over a period of only a few thousand years, suggesting that chemical synthesis of complex organic molecules can take place over very short time scales (PDF file). We were also able to measure the precise emission profile of the unidentified 21 micron emission feature (PDF file) that we first discovered with the IRAS satellite in 1989 (PDF file).

Atlas of SWS Spectra

Articles:

News conference in Atlanta, January 2000

Science and Technology Article, Jan 2001