The star
The star
K2-133
- Type
- M1.5 V
- Surface
- ≈ 3,655 K
- Size
- 0.46 × the Sun
- Mass
- 0.46 × the Sun
- Brightness
- 0.0332 × the Sun
- Habitable zone
- 0.149–0.383 AU
The planets
K2-133
K2-133 b
- Year
- 3.07 days
- Distance from star
- 0.0319 AU
- Mass
- 2.4 Earths
- Size
- 1.3 × Earth
- Temperature
- ≈ 665 K (+392 °C)
- Found
- 2017, transit (K2)
K2-133
K2-133 c
- Year
- 4.87 days
- Distance from star
- 0.0434 AU
- Mass
- 3.2 Earths
- Size
- 1.6 × Earth
- Temperature
- ≈ 571 K (+297 °C)
- Found
- 2017, transit (K2)
K2-133
K2-133 d
- Year
- 11.02 days
- Distance from star
- 0.0749 AU
- Mass
- 4.7 Earths
- Size
- 2 × Earth
- Temperature
- ≈ 734 K (+461 °C)
- Found
- 2017, transit (K2)
K2-133
K2-133 e
- Year
- 26.58 days
- Distance from star
- 0.135 AU
- Mass
- 3.6 Earths
- Size
- 1.7 × Earth
- Temperature
- ≈ 296 K (+23 °C)
- Found
- 2019, transit (K2)
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.