K2-3 d is a terrestrial world located approximately 144 light-years away in the constellation Leo. It is part of a three-planet system discovered by the Kepler Space Telescope during its extended mission.
Key Physical Characteristics
- Planet Type: Terrestrial (rocky) Super-Earth.
- Size: It is about 1.5 times the radius of Earth.
- Mass: It is estimated to be roughly 7.5 times the mass of Earth, making it a very dense and heavy world.
- Orbit: It completes one orbit around its star every 44.6 Earth days.
- The Star: K2-3 is a bright, relatively quiet red dwarf (M-dwarf).
Habitability & Environment
In Lisa Kaltenegger’s research, K2-3 d is a critical case study for the inner edge of habitability:
- Location: It sits on the inner boundary of the habitable zone.
- Energy Intake: It receives about 1.4 to 1.5 times the starlight that Earth gets from the Sun. This makes it a “warm” Earth, potentially similar to a cooler version of Venus.
- Atmosphere: Because the planet is so massive and dense, it has a high surface gravity, which would help it hold onto a very thick atmosphere. Scientists are eager to know if this atmosphere is filled with clouds that reflect heat or greenhouse gases that trap it.
Scientific Significance
- Bright Star Advantage: The host star is one of the brightest red dwarfs known to host planets. This makes K2-3 d one of the best targets for telescopes to “see” through its atmosphere as it transits the star.
- Density Mystery: Its high density suggests a very rocky composition with a potentially large iron core.
- Comparative Science: By studying K2-3 d alongside its two inner siblings (which are much hotter), Kaltenegger and her team can model how atmospheric loss changes as you move further away from a star.
