The star
The star
Kepler-221
- Type
- orange dwarf
- Surface
- ≈ 5,243 K
- Size
- 0.82 × the Sun
- Mass
- 0.85 × the Sun
- Brightness
- 0.394 × the Sun
- Habitable zone
- 0.486–1.16 AU
The planets
Kepler-221
Kepler-221 b
- Year
- 2.80 days
- Distance from star
- 0.037 AU
- Mass
- 6 Earths
- Size
- 1.7 × Earth
- Temperature
- ≈ 1090 K (+817 °C)
- Found
- 2014, transit (Kepler)
Kepler-221
Kepler-221 c
- Year
- 5.69 days
- Distance from star
- 0.059 AU
- Mass
- 9.3 Earths
- Size
- 2.9 × Earth
- Temperature
- ≈ 860 K (+587 °C)
- Found
- 2014, transit (Kepler)
Kepler-221
Kepler-221 d
- Year
- 10.04 days
- Distance from star
- 0.087 AU
- Mass
- 3.6 Earths
- Size
- 2.7 × Earth
- Temperature
- ≈ 712 K (+439 °C)
- Found
- 2014, transit (Kepler)
Kepler-221
Kepler-221 e
- Year
- 18.37 days
- Distance from star
- 0.13 AU
- Mass
- 7.9 Earths
- Size
- 2.6 × Earth
- Temperature
- ≈ 582 K (+309 °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.