Astronomers detected a thin atmosphere around the distant object 2002 XV93, located beyond Pluto's orbit. The discovery emerged from observations of a stellar eclipse, where the object passed in front of a star and its light dimmed in a pattern consistent with atmospheric refraction.
The research team used ground-based telescopes to monitor the star's brightness during the occultation event. When a stellar body blocks starlight directly, its shadow produces a sharp cutoff. Instead, the team observed a gradual dimming and brightening, indicating light had bent through atmospheric layers surrounding 2002 XV93. This signature proves the presence of a gaseous envelope around the object.
2002 XV93 belongs to a class of distant icy bodies known as plutinos, objects that orbit in a 2:3 resonance with Neptune. The object measures roughly 640 kilometers across, making it substantially smaller than Pluto but large enough to potentially retain an atmosphere. Researchers believe the thin atmosphere likely consists of nitrogen, methane, or carbon monoxide frozen at the object's surface and sublimating into gas due to distant solar heating or internal processes.
This discovery marks the first confirmed atmosphere detection on a solar system body orbiting farther from the sun than Pluto. Previous atmospheric detections focused on closer objects like Saturn's moon Titan or Neptune's moon Triton. The finding expands understanding of which distant bodies can sustain atmospheric conditions and challenges assumptions about atmospheric retention in the cold outer solar system.
The occultation method provides a powerful tool for studying distant objects where traditional spectroscopy struggles. Future observations of similar stellar eclipses could reveal whether other distant icy bodies possess atmospheres, potentially transforming the known inventory of atmospheric worlds in our solar system.
The research demonstrates that even bodies in the frigid outer reaches maintain dynamic surface-atmosphere interactions.
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