On Campus | Alumni
Comets represent relatively unprocessed material left over from the formation of planets, so their study can offer clues to understanding the history of our solar system. The primary volatile constituent in a comet is water ice, which can be difficult to observe from ground-based telescopes. The radio (18cm) lines of OH, a direct photo-dissociation "daughter" product of water, can be observed easily, unaffected by sunlight or most weather conditions, as a proxy for its water parent. Using both the Arecibo 305m radiotelescope and the National Radio Astronomy Observatory (NRAO) 100m Green Bank Telescope, we have undertaken a decade-long survey of OH spectra from more than 25 comets, to analyze with a simple kinematic model. Results from model fits include assessment of the outflow velocity of the gas, the total production of molecules from both the day and night sides of the nucleus, and constraints on the effects of in the dense inner coma. These results are interesting when well-sampled across a range of conditions, and also serve to support observations of the same comets at other wavelengths, where gas production and velocities are not easily are not easily measured. I will outline the features of the model and an overview of the results of the survey to date.