The star
The star
Kepler-261
- Type
- orange dwarf
- Surface
- ≈ 5,098 K
- Size
- 0.79 × the Sun
- Mass
- 0.83 × the Sun
- Brightness
- 0.338 × the Sun
- Habitable zone
- 0.453–1.09 AU
The planets
Kepler-261
Kepler-261 b
- Year
- 10.38 days
- Distance from star
- 0.088 AU
- Mass
- 5.4 Earths
- Size
- 2.2 × Earth
- Temperature
- ≈ 672 K (+399 °C)
- Found
- 2014, transit (Kepler)
Kepler-261
Kepler-261 c
- Year
- 24.57 days
- Distance from star
- 0.156 AU
- Mass
- 4.7 Earths
- Size
- 2 × Earth
- Temperature
- ≈ 505 K (+232 °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.