Program: GN-2011B-Q-16

We seek GMOS-N time to obtain target-of-opportunity spectroscopy of up to 2 bright newly-discovered main-belt comets (MBCs) to confirm the sublimation-driven nature of their activity by detecting CN emission at 3889 Angstroms. As a recently-identified class of objects that exhibit comet-like activity yet are dynamically indistinguishable from main-belt asteroids, these poorly understood objects blur the classical lines between asteroids and comets, and may have played a significant role in the primordial delivery of Earth's water. To date, it has never been unambiguously shown that MBC activity is due to the sublimation of ice, though abundant indirect evidence supports this conclusion. If observed promptly, newly discovered main-belt comets that are sufficiently bright and exhibit substantial coma offer excellent opportunities to detect gas emission from a main-belt object and provide the first unambiguous confirmation of present-day volatile material in the main belt. In this proposal, we request UH and Gemini time to observe up to two MBCs from Gemini-North. A companion proposal has been submitted to NOAO to observe up to two MBCs from Gemini-South. This is a continuation of a 2011A ToO proposal for which no observations have yet been made.