# A molecular wind blows out of the Kuiper belt

**Authors:** Quentin Kral, J. E. Pringle, Aurélie Guilbert-Lepoutre, Luca Matrà, Julianne I. Moses, Emmanuel Lellouch, Mark C. Wyatt, Nicolas Biver, Dominique Bockelée-Morvan, Amy Bonsor, Franck Le Petit, G. Randall Gladstone  
**arXiv:** [2104.01035](https://arxiv.org/abs/2104.01035)  
**Date:** 2021-04-02  
**Summary page:** https://www.summarizepaper.com/en/paper/2104.01035v2/

## Key points

- Gas has been detected in many exoplanetary systems, believed to be released during the destruction of volatile-rich planetesimals orbiting in exo-Kuiper belts.
- Researchers aimed to explore whether gas is also expected in the Kuiper belt (KB) in our Solar System.
- Only bodies larger than about 4 km can still contain CO ice after 4.6 Gyr of evolution, which may explain why Jupiter-family comets are deficient in CO compared to Oort-clouds comets.
- Gas is currently produced in the KB at a rate of $2 \times 10^{-8}$ M$_\oplus$/Myr for CO and orders of magnitude more when the Sun was younger.
- A molecular gas wind blowing out from our Solar System starting at the KB location and extending far beyond with regards to the heliosphere exists with a current total CO mass of $\sim 2 \times 10^{-12}$ M$_\oplus$, as well as an atomic gas wind made of carbon and oxygen (neutral and ionized) with a mass of $\sim 10^{-11}$ M$_\oplus$.
- The model developed for gas release due to slow heating may work for exoplanetary systems and provide the first real physical mechanism for the gas observations seen around other stars.
- Recent observations of the KB have shown that it is a complex and dynamic environment with a variety of objects ranging from small planetesimals to dwarf planets.
- Understanding not only our own Solar System's Kuiper belt but also those around other stars could shed light on their formation and evolution processes too.

## Summary

Gas has been detected in many exoplanetary systems, believed to be released during the destruction of volatile-rich planetesimals orbiting in exo-Kuiper belts. In a recent letter published in Astronomy & Astrophysics, researchers aimed to explore whether gas is also expected in the Kuiper belt (KB) in our Solar System. To quantify the gas release in our Solar System, they used models for gas release that have been applied to extrasolar planetary systems, as well as a physical model that accounts for gas released due to the progressive internal warming of large planetesimals. The study found that only bodies larger than about 4 km can still contain CO ice after 4.6 Gyr of evolution. This finding may provide a clue as to why Jupiter-family comets, thought to originate in the Kuiper belt, are deficient in CO compared to Oort-clouds comets. The researchers predicted that gas is still produced in the KB right now at a rate of $2 \times 10^{-8}$ M$_\oplus$/Myr for CO and orders of magnitude more when the Sun was younger. Once released, the gas is quickly pushed out by the Solar wind. Therefore, they predict a molecular gas wind blowing out from our Solar System starting at the KB location and extending far beyond with regards to the heliosphere with a current total CO mass of $\sim 2 \times 10^{-12}$ M$_\oplus$. They also predict the existence of a slightly more massive atomic gas wind made of carbon and oxygen (neutral and ionized) with a mass of $\sim 10^{-11}$ M$_\oplus$. The study predicts that gas is currently present beyond the Kuiper belt and although it cannot be detected with current instrumentation, it could be observed in future missions using an instrument similar to Alice on New Horizons with larger detectors. The model developed for gas release due to slow heating may also work for exoplanetary systems and provide the first real physical mechanism for the gas observations seen around other stars. In addition, recent observations of the KB have shown that it is a complex and dynamic environment with a variety of objects ranging from small planetesimals to dwarf planets. The researchers suggest that their findings could help explain some of these phenomena such as dust and gas clouds observed within it. The study also highlights how important it is to understand not only our own Solar System's Kuiper belt but also those around other stars since this knowledge could shed light on their formation and evolution processes too. This topic will be explored further by some authors involved in this paper who plan on investigating how gases released from planetesimals within these belts can affect their dynamical structure going forward.