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Japan Astronomers Find Evaporating Atmosphere on TNO

5/6/2026

Summary

Arimatsu Detects Atmosphere

Japan’s astronomers led by Ko Arimatsu reported that trans-Neptunian object (612533) 2002 XV93 possesses a thin atmosphere.
The team observed the occultation of a 15-magnitude star on 10 January 2024 from four Japanese sites.
The gradual dimming showed an atmosphere 5-10 million times thinner than Earth’s and predicted it would vanish within 1,000 years if not replenished.
The findings, published in Nature Astronomy on 4 May 2026, challenge the view that only large dwarf planets retain atmospheres.

Summary

Japanese Observatories Capture

A coordinated network of four Japanese observatories captured the 2024 occultation of (612533) 2002 XV93 with high-speed photometry.
Researchers used the Lucky Star pipeline and SORA software for reduction, streamlining detection of tenuous atmospheres.
The success builds on prior amateur occultations, such as the 2019 Arimatsu et al. discovery, and validates the OASES system for regular monitoring of plutino atmospheres.

History

Historical Context

In 1988, James Elliot and the Lowell Observatory proved Pluto’s atmosphere by a stellar occultation, measuring a surface pressure of about 1.5 µbar (?0.001 % of Earth’s). Subsequent occultations in 2002 showed pressure roughly doubled, establishing the technique’s value. Today Ko Arimatsu’s team applies the same method to TNO 2002 XV93, using four sites and the Lucky Star pipeline to detect an ultra-thin atmosphere.

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Arimatsu Detects Atmosphere

Japan’s astronomers led by Ko Arimatsu reported that trans-Neptunian object (612533) 2002 XV93 possesses a thin atmosphere.
The team observed the occultation of a 15-magnitude star on 10 January 2024 from four Japanese sites.
The gradual dimming showed an atmosphere 5-10 million times thinner than Earth’s and predicted it would vanish within 1,000 years if not replenished.
The findings, published in Nature Astronomy on 4 May 2026, challenge the view that only large dwarf planets retain atmospheres.

1 / 3