The star
The star
Kepler-198
- Type
- yellow star
- Surface
- ≈ 5,574 K
- Size
- 0.94 × the Sun
- Mass
- 0.99 × the Sun
- Brightness
- 0.778 × the Sun
- Habitable zone
- 0.67–1.59 AU
The planets
Kepler-198
Kepler-198 d
- Year
- 1.31 days
- Distance from star
- 0.0234 AU
- Mass
- 3 Earths
- Size
- 1.5 × Earth
- Temperature
- ≈ 1562 K (+1289 °C)
- Found
- 2016, transit (Kepler)
Kepler-198
Kepler-198 b
- Year
- 17.79 days
- Distance from star
- 0.131 AU
- Mass
- 8.3 Earths
- Size
- 2.8 × Earth
- Temperature
- ≈ 655 K (+382 °C)
- Found
- 2014, transit (Kepler)
Kepler-198
Kepler-198 c
- Year
- 49.57 days
- Distance from star
- 0.259 AU
- Mass
- 6.7 Earths
- Size
- 2.5 × Earth
- Temperature
- ≈ 465 K (+192 °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.