Early Results from SOFIA/EXES High Resolution Spectroscopic Observations of Circumstellar Envelopes of AGB Stars

We present early results from our project to investigate if there is a relationship between the mass-loss rates of AGB stars and the chemistry within the circumstellar envelopes that this process creates. We have obtained high spectral resolution (R > 60,000) observations with the Echelon Cross Echelle Spectrograph (EXES) aboard SOFIA of a small sample of C, M, and S-type AGB stars. The mass-loss rate of this sample ranges from 10^-7 to 10^-5 solar masses per year. We have focused on two spectral regions (7.5 & 13—14 μm) that allow us to study several molecules that are either exceedingly difficult to observe from the ground or have no permanent dipole moment.