The star
The star
Kepler-51
- Type
- yellow star
- Surface
- ≈ 5,674 K
- Size
- 0.87 × the Sun
- Mass
- 0.96 × the Sun
- Brightness
- 0.722 × the Sun
- Habitable zone
- 0.641–1.52 AU
The planets
Kepler-51
Kepler-51 b
- Year
- 45.15 days
- Distance from star
- 0.251 AU
- Mass
- 2.1 Earths
- Size
- 7.1 × Earth
- Temperature
- ≈ 543 K (+270 °C)
- Found
- 2012, transit (Kepler)
Kepler-51
Kepler-51 c
- Year
- 85.31 days
- Distance from star
- 0.384 AU
- Mass
- 4 Earths
- Size
- 9 × Earth
- Temperature
- ≈ 439 K (+166 °C)
- Found
- 2012, transit (Kepler)
Kepler-51
Kepler-51 d
- Year
- 130.19 days
- Distance from star
- 0.509 AU
- Mass
- 7.6 Earths
- Size
- 9.7 × Earth
- Temperature
- ≈ 381 K (+108 °C)
- Found
- 2014, transit (Kepler)
Kepler-51
Kepler-51 e
- Year
- 264.28 days
- Distance from star
- 0.795 AU
- Mass
- 5.4 Earths
- Size
- 2.2 × Earth
- Found
- 2024, transit timing variations (Multiple Observatories)
Masses found by the wobble method are minimums, because the orbit's tilt is unknown. Temperatures are equilibrium estimates for a bare planet, before any atmosphere.
How we know
The shadow
The planet passes in front of its star and dims it by a fraction of a percent, every orbit. The dip gives the planet's size and year.
Early and late
A known planet arrives early or late for its transits, betraying the pull of another, unseen planet.
Sources
- Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 1 Nov 2026. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.
- Position: HYG Database v4.1 (CC BY-SA 4.0).
- Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.