La Jornada: Astronomers believe they have detected an atmosphere around a small world beyond Pluto

Cape Canaveral. A new study suggests that a small icy world beyond Pluto harbors a thin, delicate atmosphere that may have been created by volcanic eruptions or a comet impact.

At just about 500 kilometers in diameter, this mini-Pluto is believed to be the smallest object in the solar system to date with a clearly detected global atmosphere held in place by gravity, said lead researcher Ko Arimatsu of the National Astronomical Observatory of Japan.

“This is an astonishing advance, but it urgently needs independent verification. The implications would be profound if confirmed,” said Alan Stern of the Southwest Research Institute, principal scientist for NASA’s New Horizons mission to Pluto and beyond. Stern was not involved in the study.

This finding offers a new perspective on the coldest and most distant objects in our solar system, located in a region known as the Kuiper Belt. Researchers used three telescopes in Japan to observe the object in 2024, when it passed in front of a background star, briefly dimming its brightness. This minor planet – formally known as (612533) 2002 XV93 – is considered a plutinous that orbits the Sun twice in the time it takes Neptune to complete three solar orbits. At the time of the study, it was more than 5.5 billion kilometers away, even farther than Pluto, the only other Kuiper Belt object with an observed atmosphere.

According to a study published yesterday in the journal Nature Astronomythe atmosphere of this cosmic ice ball is believed to be 5 to 10 million times thinner than Earth’s protective atmosphere.

It is between 50 and 100 times fainter than Pluto’s own atmosphere. The most likely atmospheric chemicals are methane, nitrogen or carbon monoxide, any of which could reproduce the dimming observed when the object passed in front of the star, Arimatsu said.

According to Arimatsu, new observations, especially those made by NASA’s Webb Space Telescope, could verify the composition of the atmosphere.

“That is why future monitoring is so important,” he stated. “If the atmosphere fades in the coming years, that would support an impact origin. If it persists or varies seasonally, that would rather point to a continuous internal supply of gas” from ice volcanoes.