The star
The star
KOI-1257
- Type
- G5 V
- Surface
- ≈ 5,520 K
- Size
- 1.13 × the Sun
- Mass
- 0.99 × the Sun
- Brightness
- 1.07 × the Sun
- Habitable zone
- 0.788–1.87 AU
The planets
KOI-1257
KOI-1257 b
- Year
- 86.65 days
- Distance from star
- 0.382 AU
- Mass
- 1.5 Jupiters
- Size
- 11 × Earth
- Temperature
- ≈ 511 K (+238 °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.