The star
The star
WISEP J121756.91+162640.2 A
- Type
- T8.5
- Surface
- ≈ 575 K
- Size
- 0.09 × the Sun
- Mass
- 0.03 × the Sun
- Brightness
- 8.13e-07 × the Sun
- Habitable zone
- 0.00086–0.00151 AU
The planets
WISEP J121756.91+162640.2 A
WISEP J121756.91+162640.2 A b
- Year
- 132.9 years
- Distance from star
- 8 AU
- Mass
- 22 Jupiters
- Size
- 10 × Earth
- Temperature
- ≈ 450 K (+177 °C)
- Found
- 2012, imaging (W. M. Keck 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
A direct picture
The star's glare is blocked or subtracted, leaving the planet's own faint light as a dot that moves along its orbit over the years.
Sources
- Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 31 Oct 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.