Determining nucleus ice associations in comets through the spatial distribution of volatiles in the coma

Long-slit high-resolution infrared spectroscopy has been used to obtain insights into the sources of volatiles seen in the comae of comets since the apparitions of comets C/1995 O1 Hale-Bopp and C/1996 B2 Hyakutake over twenty-five years ago. Determining the distributions of the emission flux of individual ro-vibrational lines along the slit provided a means of investigating whether or not volatile species had additional (extended) sources and allowed for assessing optical depth effects. These studies were limited to the brightest comets where sufficient emission flux could be measured to distances well off the nucleus. Modern infrared spectrometers have extended spatial studies to a larger population of moderately bright comets, and to more molecules within the brightest comets. This has revealed information about how volatiles are released into the coma as well as likely associations between volatiles while they were stored in the nucleus. As more comets have been observed, such measurements have started to reveal which spatial properties and volatile associations are unique to individual comets or common to the population. Here, we compare the molecular coma spatial distributions and possible nucleus ice associations in comets C/2014 Q2 Lovejoy, C/2012 S1 ISON, 153P/Ikeya-Zhang, 103P/Hartley 2, and 73P/Schwassmann-Wachmann-3 B & C. The authors acknowledge support by the NASA Emerging Worlds and Solar System Observations Programs and the NSF Astronomy and Astrophysics Program.