K2-131 b
K2-131 b is a lava world orbiting K2-131 in the constellation Virgo. It lies about 497 light-years from Earth and was discovered in 2017 using the transit method.
How Big Is K2-131 b?
K2-131 b has a radius of 1.69 times that of Earth. Its mass is 7.9 times that of Earth, giving it a density of 8.80 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is K2-131 b in the Habitable Zone?
K2-131 b orbits inside the inner edge of the habitable zone of K2-131. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-131: 0.464–1.118 AU (conservative: 0.588–1.060 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-131 b
The equilibrium temperature of K2-131 b is about 2,223 K (1,950 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 4,070 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on K2-131 b — one full orbit around K2-131 — lasts just 8.9 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.009 AU — closer to its star than Mercury is to the Sun.
How Was K2-131 b Discovered?
K2-131 b was discovered in 2017 using the transit method, with observations from K2.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is K2-131 b?
K2-131 b is 497.4 light-years (152.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1529. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 8,754,240 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. K2-131 b scores 0.27, ranking #2,603 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-131
K2-131
- Surface temperature
- 5,120 K (Sun: 5,772 K)
- Mass
- 0.80 M☉
- Radius
- 0.76 R☉
- Age
- 5.3 billion years (Sun: 4.6)
Planetary System
K2-131 b is the only planet known to orbit K2-131 so far.
K2-131 b — Complete Data
| Radius | 1.690 Earth radii (0.151 Jupiter radii) |
|---|---|
| Mass | 7.90 Earth masses (0.025 Jupiter masses) |
| Density | 8.80 g/cm³ (Earth: 5.51) |
| Orbital period | 0.37 days |
| Orbital distance | 0.009 AU |
| Equilibrium temperature | 2,223 K (1,950 °C) |
| Stellar irradiation | 4,070.00× Earth |
| Earth Similarity Index | 0.27 |
| Distance from Earth | 497.4 light-years (152.5 parsecs) |
| Constellation | Virgo |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2023-04-17. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-131 b
Is K2-131 b habitable?
No — K2-131 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-131 b?
K2-131 b is about 497 light-years from Earth in the constellation Virgo. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 8,754,240 years to get there.
How big is K2-131 b compared to Earth?
K2-131 b has 1.69 times the radius of Earth and about 7.9 times its mass.
How long is a year on K2-131 b?
One orbit around K2-131 takes 0.4 Earth days — short enough that 989 of its years would fit into one Earth year.
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