Organic Synthesis in the Late Stages of Stellar Evolution

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Infrared spectroscopic observations of the stretching and bending modes of aliphatic and aromatic compounds are now seen throughout the Universe, from the circumstellar envelopes of stars to the diffuse interstellar medium of the Milky Way Galaxy to distant galaxies. As much as 20% of the energy output of some galaxies is emitted in these bands. As we are also looking back in time, their detection in distant galaxies suggest that synthesis of complex organics has already taken place in the Universe 10 billion years ago.******Observations of evolved stars have revealed a rapid (thousands year time scale) and continuous synthesis of organic materials in the late stages of stellar evolution, specifically from the end of the asymptotic giant branch, to proto-planetary nebulae, to planetary nebulae. These synthesized products are ejected into the interstellar medium through stellar winds and as a result have enriched the Galaxy with complex organics.******Analysis of the infrared spectra suggests that the chemical structure of the carrier is consistent with that of mixed aromatic and aliphatic nanoparticles (MAON). These structures are very similar to those of the insoluble organic matter found in meteorites, organics on the surface of Titan, cometary dust, and interplanetary dust particles, suggesting that the early solar system may have been enriched by stellar ejecta.******As part of an interdisciplinary research program, we will obtain spectroscopic observations of astronomical sources in the infrared and submm, perform data analysis of data from recent planetary missions, and undertake quantum chemistry calculations to determine the vibrational spectra of complex organics for comparison with observed data. Our goals are to identify the chemical structure of stellar organics, to determine their chemical pathways of synthesis, to explore their relationship with Solar System organics, and to investigate their possible effects on the primordial Earth. **