KELT-11b: A planet 40% larger than Jupiter but only 1/5th its mass!
Key Takeaways
- Astronomers discovered KELT-11b, a “puffy” exoplanet with the density of styrofoam.
- KELT-11b is 40% larger than Jupiter but has only a fifth of its mass.
- Its unusually inflated size may reveal how such lightweight exoplanets evolve.
- The planet’s host star, KELT-11, is extremely bright and nearing the red giant phase.
- KELT-11b orbits very close to its star and will likely be engulfed within 100 million years.
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A Giant, Lightweight World
Astronomers have uncovered one of the lightest and most inflated exoplanets ever discovered: KELT-11b. Located about 320 light-years away, this gas giant is larger than Jupiter but has an extraordinarily low mass, giving it a density similar to styrofoam. Despite being only a fifth as massive as Jupiter, KELT-11b is 40% larger in size, thanks to its expanded, lightweight atmosphere.
This extraordinary exoplanet is one of the least dense planets with a precisely measured mass and radius, making it a valuable find for understanding how such “puffy planets” form and evolve. According to Joshua Pepper, an astronomer from Lehigh University, KELT-11b’s characteristics provide insights into atmospheric inflation mechanisms.
Host Star’s Brightness and Implications
One of KELT-11b’s unique features is its host star, KELT-11, which is undergoing a transformation into a red giant. This evolutionary phase means the star is consuming its remaining nuclear fuel, a process that will eventually lead to the engulfment of KELT-11b within the next 100 million years.
KELT-11b orbits extremely close to its star, completing a full orbit in under five days. This proximity, coupled with the star’s intense brightness, makes the exoplanet a prime candidate for studying atmospheric composition. The star, KELT-11, is the brightest known host of a transiting planet in the Southern Hemisphere, making KELT-11b’s discovery both a challenge and an opportunity for astronomers.
Challenges and Future Research
The planet’s discovery was not straightforward. The transit of KELT-11b — its passage between its host star and Earth — caused a minimal dip in the star’s brightness, making it difficult to detect using the Kilodegree Extremely Little Telescope (KELT) survey. This minuscule dip, measuring less than 0.3% in brightness, required follow-up observations to confirm KELT-11b’s existence.
Now that the planet has been identified, its highly inflated atmosphere could help scientists understand why some exoplanets expand to such extreme sizes. The intense brightness of KELT-11 enables detailed atmospheric studies, which may uncover clues about how lightweight planets like KELT-11b form and behave in the late stages of their star’s life cycle.
Astronomers also hope to learn more about planetary systems in their final stages, as KELT-11b’s star evolves and changes. This unique planet serves as a natural laboratory for studying exoplanetary atmospheres and the dynamics of planetary systems near the end of their lifespan.
The findings are reported in The Astronomical Journal.
