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Molecular Gas In The Circumstellar Environment Of Unusual Evolved Stars, Sarah E. Malek

Electronic Thesis and Dissertation Repository

As low- and intermediate mass stars (with masses up to 8-9 solar masses) age, they experience a series of evolutionary changes which culminate in the removal of nearly their entire envelope through extensive mass loss. The ejected material cools down, which allows for the formation of molecules and the nucleation of dust grains in the circumstellar environment (CSE) of the star. Much about the properties and composition of the gas and dust in these CSEs is not well understood.

Here, we study the rich CSEs of two unusual evolved stars by analyzing spectral observations in the infrared and using molecular …