A Predicted Dearth of Majority Hypervolatile Ices in Oort Cloud Comets

TL;DR

This study predicts that hypervolatile ices like CO, N$_2$, and CH$_4$ are rare in Oort Cloud comets, based on new gas coma limits from a recent space mission, impacting our understanding of comet origins and early Solar System processes.

Contribution

It introduces new gas production limits from the MU69/Arrokoth flyby to predict the scarcity of hypervolatile ices in Oort Cloud comets, offering insights into their formation and evolution.

Findings

Hypervolatile ices are predicted to be rare in Oort Cloud comets.

Ultra-distant active comets are expected to be uncommon.

Interstellar object 2I/Borisov likely did not originate from a CO-rich system.

Abstract

We present new, ice species-specific New Horizons/Alice upper gas coma production limits from the 01 Jan 2019 MU69/Arrokoth flyby of Gladstone et al. (2021) and use them to make predictions about the rarity of majority hypervolatile (CO, N$_2$, CH$_4$) ices in KBOs and Oort Cloud comets. These predictions have a number of important implications for the study of the Oort Cloud, including: determination of hypervolatile rich comets as the first objects emplaced into the Oort Cloud; measurement of CO/N$_2$/CH$_4$ abundance ratios in the proto-planetary 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 ultra-distant active comets like C/2017K2 (Jewitt et al. 2017, Hui et al. 2018) should be rare, and thus not a general characteristic of all comets. They also suggest that interstellar object 2I/Borisov did not originate in a planetary system that was inordinately CO rich (Bodewits et al. 2020), but rather could have been ejected onto an interstellar trajectory very early in its natal system's history.