NASA (Exoplanet Catalog artwork)Kepler-51d
One of three super-puff planets in a 500-million-year-old system
Overview
Kepler-51 is a Sun-like star that is about 500 million years old. It is orbited by four planets—Kepler-51b, c, d and e—first three of which are super-puffs and have the lowest known densities of any known exoplanet. The transiting planets in the system are similar in radius to gas giants like Jupiter, but have unusually small masses for their size, only a few times greater than Earth's.
Source: Wikipedia
NASA: Kepler-51 d is a Neptune-like exoplanet that orbits a G-type star. Its mass is 7.6 Earths, it takes 130.2 days to complete one orbit of its star, and is 0.509 AU from its star. Its discovery was announced in 2014.
Why it matters
- Densities below 0.1 g/cm³ — the planets are Jupiter-sized yet only a few Earth masses.
- Hubble found their atmospheres flat and featureless, hinting at high haze layers.
- A fourth planet was uncovered in 2024 from the way it tugs on the others' transit times.
NASA puts it this way: “Kepler-51 d is a Neptune-like exoplanet that orbits an F-type star. Its mass is 7.6 Earths, it takes 130.2 days to complete one orbit of its star, and is 0.509 AU from its star. Its discovery was announced in 2014.”
Discovery & system
- Discovered
- 2014 · Transit · Kepler
- Discovery paper
- Masuda 2014
- Discoverers
- 2MASS
- Host star
- Kepler-51 · 6,018 K · 1.04 M☉
- System
- 4 known planets
- Siblings
- Kepler-51 e, Kepler-51 b, Kepler-51 c
The system
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| Kepler-51 b | 45.2 d | 0.251 AU | 0.63 R♃ | 2.1 M⊕ | 543 K |
| Kepler-51 c | 85.3 d | 0.384 AU | 0.8 R♃ | 4 M⊕ | 439 K |
| Kepler-51 d | 130.2 d | 0.509 AU | 0.87 R♃ | 7.6 M⊕ | 381 K |
| Kepler-51 e | 264.3 d | 0.817 AU | 2.18 R⊕ | 5.4 M⊕ | — |
By the numbers
- Radius
- 0.87 R♃9.7 R⊕
- Mass
- 7.6 M⊕45.39 ×10²⁴ kg
- Orbital period
- 130.2 d0.36 yr
- Distance from star
- 0.509 AU76 million km
- Eccentricity
- 0.008nearly circular
- Equilibrium temp.
- 381 K108 °C
- Starlight received
- 2 × Earth
- Distance from Earth
- 2,557 ly783.8 pc
- Density
- 0.05 g/cm³0.01 × 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.