Theses and Dissertations

Issuing Body

Mississippi State University


Pierce, Donna M.

Committee Member

Wang, Chuji

Committee Member

Monts. David L.

Date of Degree


Document Type

Graduate Thesis - Open Access



Degree Name

Master of Science


College of Arts and Sciences


Department of Physics and Astronomy


Comets are important for solar system studies because their interiors hold evidence of the conditions in which they formed in the outer solar system. However, the coma obscures the nucleus from view when observations are most easily performed, thus it is important to understand the nature of cometary comae. This study examines the spatial distribution of CN radicals in the coma of comet Encke and determines the likelihood that CN is a photodissociative daughter of HCN in the coma. Observations of CN were obtained from October 22-24, 2003, using the 2.7 m Cassegrain telescope at McDonald Observatory in Fort Davis, TX. The classical vectorial model was modified by introducing a fan-like feature in order to explain Encke’s aspherical coma. The results are consistent with HCN being the photodissociative parent of CN, based on the OH/CN ratios and the physical parameters used to match the model profiles with the observations.