New research from NASA’s Jet Propulsion Laboratory suggests there may be a volcanic moon orbiting a planet 635 light-years from Earth.
This potential exomoon, similar to Jupiter’s moon Io, could be spewing large amounts of sodium into space, creating a vast cloud around the gas giant exoplanet WASP-49 b.
The findings, which are published in The Astrophysical Journal Letters, are still preliminary, and more observations are needed to confirm the moon’s existence.
WASP-49 b is a Saturn-sized gas giant, meaning it’s mostly composed of hydrogen and helium, much like its host star.
However, what caught scientists’ attention was a large sodium cloud around the planet.
This cloud was first detected in 2017, sparking the curiosity of Apurva Oza, a former postdoctoral researcher at NASA’s Jet Propulsion Laboratory, who has been investigating the possibility of detecting moons through their volcanic activity.
Volcanic moons like Io release gases, including sodium, sulfur dioxide, and potassium, which can create enormous clouds around their planets.
In the case of Io, the cloud of gas it produces is 1,000 times the radius of Jupiter, making it easier to detect. A similar phenomenon might be happening with WASP-49 b, where the sodium cloud suggests a hidden volcanic exomoon.
While no exomoon (a moon orbiting a planet outside our solar system) has been confirmed, scientists have found several possible candidates.
Most exomoons are too small and faint to be seen by current telescopes, but their presence could be hinted at through indirect observations like the sodium cloud around WASP-49 b.
Neither the planet nor its star contains enough sodium to explain the size of the cloud, which is producing an astonishing 220,000 pounds of sodium every second. Even if the star or planet could create this much sodium, there’s no known mechanism that could eject it into space in such large quantities. This led Oza and his team to investigate whether the sodium cloud might be coming from a volcanic exomoon.
Their research wasn’t easy, as the planet, star, and sodium cloud often overlap and appear as a single point in the sky from Earth’s perspective. The team had to carefully track the system over time to understand how the cloud behaved.
The researchers found that the sodium cloud didn’t always behave as expected. At times, it grew larger, as though it had been “refueled,” and it moved faster than the planet, which would be impossible if it were part of the planet’s atmosphere.
These irregularities suggest the cloud is being generated by something other than the planet, possibly a moon orbiting WASP-49 b.
“The cloud is moving in the opposite direction to what physics tells us it should if it were part of the planet’s atmosphere,” said Oza, calling this a critical piece of evidence for the existence of a volcanic exomoon.
To further study the system, the team used the European Southern Observatory’s Very Large Telescope in Chile. Julia Seidel, a co-author of the study, confirmed that the sodium cloud is located far above the planet’s atmosphere, similar to the gas cloud created by Io around Jupiter.
The researchers also used computer models to explore the possibility of an exomoon, finding that a moon with an eight-hour orbit around WASP-49 b could explain the cloud’s movements. The cloud seemed to move independently from the planet, disappearing and reappearing at irregular intervals. This behavior further supports the theory that something other than the planet is responsible for the cloud.
On Earth, volcanic activity is driven by heat from the planet’s core, but on Io, the volcanoes are powered by Jupiter’s immense gravitational pull.
As Io moves closer to and farther from Jupiter, the moon is stretched and squeezed, producing tidal forces that heat its interior and drive volcanic eruptions. A similar process may be happening with the potential exomoon of WASP-49 b, where the planet’s gravity would cause tidal heating in the moon.
However, if this exomoon exists, its fate is likely grim. The moon could eventually lose too much mass due to volcanic activity, and the intense gravitational pull of the planet could cause it to break apart. “If there really is a moon there, it will have a very destructive ending,” said Oza.
This research opens up exciting possibilities for discovering and studying volcanic exomoons in distant star systems, offering new insights into the dynamic and sometimes violent processes that shape planets and their moons.
Source: NASA.
