Astronomers have discovered signs of a thin atmosphere surrounding a small icy object beyond the orbit of Neptune, a finding that could change current understanding of how distant objects in the Solar System behave and evolve, reported BBC.
The object, known as (612533) 2002 XV93, is located in the Kuiper Belt and is only around 500 kilometres (310 miles) across. It is much smaller than Pluto, which measures about 2,377 kilometres (1,477 miles) across.
Scientists generally believe that objects this small do not have enough gravity to hold on to an atmosphere for long periods. The discovery was made by a team of professional and amateur astronomers led by Ko Arimatsu at the National Astronomical Observatory of Japan.
The researchers observed 2002 XV93 from multiple locations across Japan as it passed in front of a distant star in January 2024. During this event, known as a stellar occultation, astronomers study how the light from a star changes as an object moves in front of it. A sharp disappearance of starlight usually suggests there is no atmosphere, while a gradual dimming indicates the presence of gas surrounding the object.
The team found that the data matched what would be expected if a thin atmosphere were present. The researchers said that a thin atmosphere has been observed around Pluto, but studies of other trans-Neptunian objects (TNOs) have not found similar evidence.
According to their calculations, any atmosphere around 2002 XV93 should survive for less than 1,000 years unless it is constantly replenished, suggesting that it must have formed recently.
However, observations by the James Webb Space Telescope found no evidence of frozen surface gases that could slowly evaporate and maintain such an atmosphere.
The researchers proposed two possible explanations. One is that material from deep inside the object may recently have reached the surface and released gas. The other is that a comet impact may have blasted material into space, temporarily creating an atmosphere.
The study marks the first-ever detection of a potential atmosphere around a trans-Neptunian object other than Pluto.
The researchers said future observations should help determine how the atmosphere formed and whether similar processes may occur on other distant icy worlds.
