The star
The star
Kepler-1921
- Type
- white star
- Surface
- ≈ 6,120 K
- Size
- 2.00 × the Sun
- Mass
- 1.25 × the Sun
- Brightness
- 6.4 × the Sun
- Habitable zone
- 1.86–4.35 AU
The planets
Kepler-1921
Kepler-1921 c
- Year
- 3.16 days
- Distance from star
- 0.0454 AU
- Mass
- 2.6 Earths
- Size
- 1.4 × Earth
- Temperature
- ≈ 1791 K (+1518 °C)
- Found
- 2023, transit (Kepler)
Kepler-1921
Kepler-1921 b
- Year
- 20.03 days
- Distance from star
- 0.159 AU
- Mass
- 8.7 Earths
- Size
- 2.9 × Earth
- Temperature
- ≈ 967 K (+694 °C)
- Found
- 2021, 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.