Astronomers have discovered for the first time beyond Pluto a thin but rare atmosphere surrounding a small celestial body in the outer solar system.
The existence of an atmosphere around the tiny icy rock has baffled the researchers, as they had previously not considered the possibility of rocks harboring an atmosphere due to their very small size.
These icy and rocky bodies are called trans-Neptunian objects or TNOs and exist in the Kuiper Belt bordering our Solar System. These rocks are the remains of its formation 4.5 billion years ago.
2002 XV93 Icy Rock
The icy rock in question, known as 2002 XV93, is a small TNO with a diameter of about 500 kilometers, considerably smaller than Pluto (2,377 kilometers).
Using a method called stellar occultation, researchers observed the object passing in front of a distant star. Instead of the star’s light instantly blinking out, it faded and gradually reappeared, demonstrating the presence of a thin atmosphere responsible for bending the light.
“The observation data showed a smooth change in the star’s brightness near the edge of the shadow, which lasted about 1.5 seconds. This kind of smooth brightness change is naturally explained if the star’s light was diffracted by a very thin atmosphere around the object,” says Dr. Ko Arimatsu, associate professor and senior lecturer at the National Astronomical Observatory of Japan.
Speaking of the density of the atmosphere, it is estimated to be 5 to 10 million times thinner than that of the Earth.
Possible origin
According to researchers, two possible theories could justify the existence of a rarely observed atmosphere of such a small body.
The first theory is based on cyclovolcanism. The atmosphere could be the product of the release of internal gases such as methane, nitrogen or CO from beneath the icy surface by ice volcanoes.
In addition, a collision with another Kuiper Belt object can also lead to the release of subsurface gases, creating a temporary atmosphere.
The findings published in the journal Nature Astronomy are important as if they are confirmed they can challenge the status quo regarding small worlds.
The discovery also proves that even smaller objects in the Kuiper Belt can harbor an atmosphere, demonstrating active geological activity in the outer solar system.
The discovery proves that even small objects in the Kuiper Belt can maintain an atmosphere, indicating that the outer solar system is more geologically active than previously thought.
Future plans
To investigate its true origins and nature, astronomers plan to use the James Webb Space Telescope to identify the chemical composition of the atmosphere and monitor its pressure.
Dr. Scott S. Sheppard, a staff scientist at the Carnegie Institution for Science in Washington, DC, said: “This shows that the Kuiper Belt is not a cold, dead place, but is bustling with activity and contains many of the building blocks for life.”
