The star
The star
K2-157
- Type
- G9 V
- Surface
- ≈ 5,334 K
- Size
- 0.86 × the Sun
- Mass
- 0.89 × the Sun
- Brightness
- 0.616 × the Sun
- Habitable zone
- 0.604–1.44 AU
The planets
K2-157
K2-157 b
- Year
- 0.37 days
- Distance from star
- 0.00962 AU
- Mass
- 1.1 Earths
- Size
- 0.94 × Earth
- Temperature
- ≈ 2432 K (+2159 °C)
- Found
- 2018, transit (K2)
K2-157
K2-157 c
- Year
- 25.94 days
- Distance from star
- 0.165 AU
- Mass
- at least 31 Earths
- Size
- 6.1 × Earth
- Temperature
- ≈ 587 K (+314 °C)
- Found
- 2025, radial velocity (Paranal Observatory)
K2-157
K2-157 d
- Year
- 66.50 days
- Distance from star
- 0.309 AU
- Mass
- at least 23 Earths
- Size
- 5.2 × Earth
- Temperature
- ≈ 429 K (+156 °C)
- Found
- 2025, radial velocity (Paranal Observatory)
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 wobble
The planet tugs its star back and forth. Spectrographs measure the tiny shift in the star's light, which gives the planet's year and a minimum mass.
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.