The star
The star
Kepler-31
- Type
- white star
- Surface
- ≈ 6,340 K
- Size
- 1.22 × the Sun
- Mass
- 1.21 × the Sun
- Brightness
- 2 × the Sun
- Habitable zone
- 1.03–2.39 AU
The planets
Kepler-31
Kepler-31 b
- Year
- 20.86 days
- Distance from star
- 0.16 AU
- Mass
- 37 Earths
- Size
- 5.5 × Earth
- Temperature
- ≈ 781 K (+508 °C)
- Found
- 2011, transit (Kepler)
Kepler-31
Kepler-31 c
- Year
- 42.63 days
- Distance from star
- 0.26 AU
- Mass
- 4.7 Jupiters
- Size
- 5.3 × Earth
- Temperature
- ≈ 615 K (+342 °C)
- Found
- 2011, transit (Kepler)
Kepler-31
Kepler-31 d
- Year
- 87.65 days
- Distance from star
- 0.4 AU
- Mass
- 6.8 Jupiters
- Size
- 3.9 × Earth
- Temperature
- ≈ 484 K (+211 °C)
- Found
- 2014, transit (Kepler)
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.
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.