Astronomers using NASA’s powerful James Webb Space Telescope have uncovered new clues about one of the strangest planetary systems ever discovered.
About 190 light years away from Earth, two very different planets are orbiting the same star in a rare arrangement that scientists once thought should not exist.
The unusual system contains a giant “hot Jupiter” called TOI-1130c and a smaller “mini-Neptune” known as TOI-1130b. Hot Jupiters are enormous gas planets similar to Jupiter but orbit extremely close to their stars, making them intensely hot.
These giant planets are usually lonely because their strong gravity tends to push away or destroy smaller nearby planets.
But in this system, the mini-Neptune somehow survived inside the orbit of the hot Jupiter, leaving astronomers puzzled since the system was first discovered in 2020.
Now, a new study published in Astrophysical Journal Letters reveals that the smaller planet may have formed far away from its star before slowly migrating inward together with its giant companion.
The research was led by Saugata Barat from the Massachusetts Institute of Technology and involved scientists from several institutions around the world, including the University of South Queensland and Harvard & Smithsonian Center for Astrophysics.
Using the James Webb Space Telescope, researchers studied the atmosphere of the mini-Neptune for the first time. By analyzing the specific wavelengths of light absorbed by the planet’s atmosphere, they discovered large amounts of water vapor, carbon dioxide, sulfur dioxide, and traces of methane.
These heavier molecules provided an important clue about the planet’s past.
Scientists had previously believed that mini-Neptunes forming close to their stars should mostly contain lighter gases such as hydrogen and helium. However, TOI-1130b’s atmosphere was surprisingly heavy, suggesting it could not have formed where it currently orbits today.
Instead, researchers believe both planets originally formed much farther from the star, beyond a boundary known as the “frost line.” This is the region where temperatures are cold enough for water to freeze into ice.
In these icy outer regions, young planets can collect frozen material rich in water and other chemicals. Over millions of years, the planets likely slowly moved inward toward the star while keeping much of their original atmospheres intact.
The discovery gives scientists new evidence that mini-Neptunes can form beyond the frost line before migrating closer to their stars. It also helps explain how such a strange planetary pair managed to survive together.
The system itself is considered extremely rare. The two planets orbit their star every four and eight days, and their gravity constantly pulls on each other in a delicate dance known as “mean motion resonance.” This made it difficult for researchers to predict exactly when the James Webb Space Telescope could observe the planets crossing in front of their star.
After carefully combining years of observations and computer models, the team successfully captured a detailed snapshot of the mini-Neptune’s atmosphere.
The findings offer scientists an important new look at how planetary systems can evolve in ways very different from our own solar system. Researchers say TOI-1130 may represent one of the clearest examples yet of planets migrating inward together from the icy outskirts of a young star system.
Source: KSR.
