A Predicted Dearth of Majority Hypervolatile Ices in Oort Cloud Comets

Abstract

Abstract We present new, ice species-specific New Horizons/Alice upper gas coma production limits from the 2019 January 1 MU69/Arrokoth flyby of Gladstone et al. and use them to make predictions about the rarity of majority hypervolatile (CO, N2, CH4) ices in Kuiper Belt objects and Oort Cloud comets. These predictions have a number of important implications for the study of the Oort Cloud, including the determination of hypervolatile-rich comets as the first objects emplaced into the Oort Cloud, the measurement of CO/N2/CH4 abundance ratios in the protoplanetary disk from hypervolatile-rich comets, and population statistical constraints on early (<20 Myr) planetary aggregation driven versus later (>50 Myr) planetary migration driven emplacement of objects into the Oort Cloud. They imply that the phenomenon of ultradistant active comets like C/2017K2 should be rare, and thus not a general characteristic of all comets. They also suggest that interstellar object 2I/Borisov may not have originated in a planetary system that was inordinately CO rich, but rather could have been ejected onto an interstellar trajectory very early in its natal system’s history.