NASA (Exoplanet Catalog artwork)Kepler-138d
One of the first candidate water worlds, half water by volume
Overview
Kepler-138, also known as KOI-314, is a red dwarf located in the constellation Lyra, 219 light years from Earth. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission used to detect planets transiting their stars.
Source: Wikipedia
NASA: Kepler-138 d is a super Earth exoplanet that orbits a M-type star. Its mass is 2.1 Earths, it takes 23.1 days to complete one orbit of its star, and is 0.1288 AU from its star. Its discovery was announced in 2014.
Why it matters
- A 2022 study found Kepler-138 c and d too light for rock and too heavy for gas — consistent with deep oceans.
- Its water would be a hot, high-pressure steam and supercritical fluid, not Earth-like seas.
- A fourth, non-transiting planet was found from its gravitational tugs.
NASA puts it this way: “Kepler-138 d is a super Earth exoplanet that orbits an M-type star. Its mass is 2.1 Earths, it takes 23.1 days to complete one orbit of its star, and is 0.1288 AU from its star. Its discovery was announced in 2014.”
Discovery & system
- Discovered
- 2014 · Transit · Kepler
- Discovery paper
- Kipping et al. 2014
- Host star
- Kepler-138 · M1 V · 3,841 K · 0.54 M☉
- System
- 4 known planets
- Siblings
- Kepler-138 b, Kepler-138 c, Kepler-138 e
The system
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| Kepler-138 b | 10.3 d | 0.075 AU | 0.64 R⊕ | 0.07 M⊕ | 452 K |
| Kepler-138 c | 13.8 d | 0.091 AU | 1.51 R⊕ | 2.3 M⊕ | 410 K |
| Kepler-138 d | 23.1 d | 0.129 AU | 1.51 R⊕ | 2.1 M⊕ | 345 K |
| Kepler-138 e | 38.2 d | 0.18 AU | 0.8 R⊕ | 0.43 M⊕ | 292 K |
By the numbers
- Radius
- 1.51 R⊕9,620 km
- Mass
- 2.1 M⊕12.54 ×10²⁴ kg
- Orbital period
- 23.1 d0.06 yr
- Distance from star
- 0.129 AU19 million km
- Eccentricity
- 0.01nearly circular
- Equilibrium temp.
- 345 K72 °C
- Starlight received
- 3 × Earth
- Distance from Earth
- 218 ly66.9 pc
- Density
- 3.6 g/cm³0.65 × Earth
Sources
Image: NASA (Exoplanet Catalog artwork) · NASA media: generally free of copyright · image page
Text: Wikipedia (CC BY-SA 4.0). Taglines and highlights are editorial.