Astronomers have recently uncovered a remarkable planetary system around the faint orange star WASP-132, featuring two exoplanets that couldn’t be more different. One is a rocky world that completes an orbit in just over 24 hours, while the other is a frigid gas giant that takes five years to finish its orbit.
A Rocky World with a Rapid Orbit
The inner planet, known as WASP-132 c, is a super-Earth located just 1.7 million miles from its star, making it one of the closest exoplanets to its host star ever discovered. This proximity results in a rapid orbit, completing one full revolution around the star every 24 hours and 17 minutes. Despite its scorching position, which is closer than many low-Earth satellites orbit Earth, the planet’s density suggests a largely rocky composition. At 5.5 g/cm³, its bulk density is slightly heavier than Earth’s, providing a clue to its largely solid structure.
TESS space-telescope data helped confirm the planet’s presence through photometric observations, revealing that the planet’s transits last just over one hour. Additional spectroscopic follow-ups from HARPS helped establish the planet’s mass, roughly six times that of Earth. “This is the first time we have observed such a configuration,” said Dr. David Armstrong of the University of Warwick, referring to the discovery of a super-Earth within a hot-Jupiter system.
The Icy Giant on the Outskirts
In contrast, the outer planet, WASP-132 d, is an icy giant that orbits at a much greater distance. Located approximately 252 million miles away from its star—about the same distance from the Sun to the asteroid belt—this gas giant has a mass 5.2 times that of Jupiter. At such a distance, it receives less than one percent of the light that Earth gets from the Sun, leading to temperatures that could drop to hundreds of degrees below freezing.
Despite the extreme cold, this distant giant offers a unique opportunity for scientists to study a young ice giant that is still cooling. Researchers used over nine years of CORALIE spectrograph data to track the planet’s slow orbit, revealing a steady velocity trend and hinting at the possible presence of another unseen companion further out in the system. Such long-term data provide valuable insights into the behavior of distant, frozen worlds.
A Rare System for Planetary Research
The discovery of both a rocky super-Earth and a distant icy giant orbiting the same star offers a fascinating glimpse into planetary system architecture. This system challenges traditional models of planetary migration, particularly the idea that hot Jupiters—large gas giants—tend to scatter smaller planets into different orbits or even expel them from the system.
The team behind the discovery suggests that WASP-132 c might have “drifted quietly through the disk” of material surrounding the star, leaving the inner super-Earth undisturbed. This process might explain the relatively stable orbital paths of both planets. “This is a remarkable laboratory for studying the formation and evolution of multi-planetary systems,” said François Bouchy, a researcher at the University of Geneva (UNIGE).
Revealing the Chemistry of Space
This discovery also holds significant implications for the field of astrochemistry—the study of how complex organic molecules form in space. These molecules are of particular interest because they resemble the compounds found in comets and asteroids, which can potentially deliver both water and organic compounds to planets. For planets like WASP-132 d, with its icy, methane-rich clouds, these molecules can survive in the cold depths of space, possibly offering clues about the building blocks of life.
In future studies, astronomers hope to use powerful telescopes like James Webb to study the atmospheres of these exoplanets. By analyzing their transits, scientists may detect spectral signatures of methane, ethane, or even more complex organic molecules, linking planetary science with prebiotic chemistry.
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