Astronomers Detect Atmosphere on 500km Kuiper Belt Object, Challenging Models Beyond Pluto
Updated
Updated · Sky at Night Magazine · Jun 20
Astronomers Detect Atmosphere on 500km Kuiper Belt Object, Challenging Models Beyond Pluto
1 articles · Updated · Sky at Night Magazine · Jun 20
Summary
(612533) 2002 XV 93, an icy Kuiper Belt body about 500km wide, showed signs of a thin atmosphere—the first potential detection around a trans-Neptunian object other than Pluto.
January 2024 occultation data from multiple sites in Japan showed gradual starlight dimming rather than a sharp cutoff, a pattern consistent with atmospheric attenuation.
That result defies theory because an object this small should not retain gas for long; calculations put any atmosphere's lifetime at under 1,000 years unless it is being replenished.
James Webb observations found no frozen surface gases to feed such replenishment, leaving researchers to test whether interior material recently vented or a comet impact briefly created the atmosphere.
The finding suggests some distant icy worlds may be more active than expected and could force revisions to models of how small outer Solar System bodies evolve.
A tiny world beyond Neptune has a fleeting atmosphere. What mysterious event in the outer solar system created it?
If tiny, distant worlds can have atmospheres, is the edge of our solar system more active than we ever imagined?
Atmosphere Detected on 500-km Kuiper Belt Object (612533) 2002 XV93: A Paradigm Shift in Outer Solar System Science
Overview
In January 2024, Ko Arimatsu's team observed a stellar occultation event involving the Kuiper Belt object 2002 XV93. As the object passed in front of a background star, scientists noticed a gradual dimming and brightening of the star's light, rather than an abrupt change. This pattern revealed that 2002 XV93 has a global atmosphere, making it the smallest known object in the solar system with this feature. The discovery, based on the way the atmosphere refracted starlight, challenges long-held beliefs about which bodies can retain atmospheres in the outer solar system.