Astronomers have detected, for the first time, a thin atmosphere around a tiny celestial body in the outer solar system — an object previously believed to be too small to have an atmosphere.
Thousands of TNOs exist at the edge of our solar system, remnants of their formation 4.5 billion years ago.
O is the largest of these TNOs, so called because they are located beyond Neptune’s orbit.
The frigid temperatures and weak surface gravity of these small bodies led astronomers to long believe that they are not capable of retaining atmospheres — with the exception of Pluto, which has a tenuous atmosphere. Atmospheres, especially dense ones, typically form around large planets or moons, including Titan, Saturn’s largest satellite.
However, the dwarf planets Eris, Haumea, Makemake, and dwarf planet candidate Quaoar, the largest TNOs after Pluto, apparently do not have atmospheres.
During a rare observing opportunity, astronomers in Japan detected the thin layer of atmosphere surrounding a TNO known as (612533) 2002 XV 93, according to a study published in Nature Astronomy.
The unexpected discovery — made by Dr. Ko Arimatsu, associate professor and senior lecturer at the National Astronomical Observatory of Japan, and his colleagues — could offer unprecedented insight into how an atmosphere forms and remains around a small object, and change the way astronomers think about objects in the Kuiper Belt.
As January 2024 approaches, Arimatsu and his colleagues prepared for the unique opportunity to observe a trans-Neptunian object (TNO) passing in front of a bright star, as seen from Japan.
