Deep in space, 311 light-years from Earth, two "puffy" gas giants are locked in a cosmic dance—and they're the longest-period young transiting exoplanets astronomers have ever found. HD 114082 b and HD 114082 c are orbiting a star so young it has barely begun its life, yet they offer a rare window into how planets form and migrate in the earliest moments of a star system's existence.
The star they circle, HD 114082, is only about 15 million years old—a blink of an eye compared to our sun's 4.5 billion years. Around it, these two gas giants perform their gravitational tug-of-war in an orbital resonance, with one completing two orbits for every single orbit of the other. HD 114082 b takes approximately 225 days to orbit its star, while HD 114082 c takes roughly 314 days. Finding exoplanets with such long orbital periods has historically been nearly impossible using the transit method, the primary technique astronomers rely on to detect distant worlds by measuring the tiny dip in starlight as a planet passes in front of its host star.
"We have identified a strange pair of giant exoplanets," said Dr. Carlos del Burgo Díaz, lead author of the study published in The Astrophysical Journal Letters. "They stand out among the youngest detected by passing in front of their star because they take longer to complete an orbit." The inner planet sits about 20 percent closer to its star than Earth is to the sun and has Jupiter's size. The outer planet orbits at Earth's distance from its star but carries a radius 36 percent larger than Jupiter itself—and with a density more than 7.5 times less than water, it would float like a cosmic cork.
This extreme "puffiness" in both atmospheres makes them even more unusual. What makes their discovery possible is the combination of data from space-based and ground-based telescopes operated by NASA, the European Space Agency, and academic consortiums. While HD 114082 b was identified in 2022, this new study reveals HD 114082 c for the first time, allowing researchers to piece together the masses, radii, and orbital distances of both worlds.
The most intriguing puzzle these planets present is how they came to be where they are. Given the star's youth, researchers hypothesize that both exoplanets formed much farther out in the protoplanetary disk of gas and dust and then migrated inward over their young lives. This makes the HD 114082 system an invaluable laboratory for understanding how planets assemble themselves and reshape their orbits in the earliest eons of stellar existence—knowledge that could rewrite our understanding of how systems like our own came together.
The discovery opens multiple avenues for future study. Astronomers plan to use NASA's James Webb Space Telescope to analyze the atmospheres of both exoplanets, tighten the orbital period estimate for HD 114082 c (currently carrying a margin of error of about 9 percent), and dig deeper into their intricate gravitational dance. For now, these young giants remind us that the universe's diversity of worlds continues to surprise, teaching us lessons written in light across the vast distances of space.