Epsilon Indi Ab
Planet· orbits Epsilon Indi
Epsilon Indi Ab - a cold super-Jupiter of several Jupiter masses orbiting the nearby orange dwarf Epsilon Indi at about 20 AU, on a wide ~100-year orbit. In 2024 it became one of the first radial-velocity planets to be directly imaged, by JWST's mid-infrared camera. Its mass is measured, but it has never transited, so its size and appearance are model-based.
Open in 3D viewSee Epsilon Indi Ab in the live, interactive 3D map
Key facts
Mass
1.45 × 10²⁸ kg
7.63 M♃ (2,425 M⊕)
Year
108 Earth years
39,400 Earth days
Distance from Epsilon Indi
20.9 AU
Science
Physical
- Mass
- 1.45 × 10²⁸ kg · 7.63 M♃ (2,425 M⊕)
- Radius
- Not measured
- No transit — the radius is a model estimate (~1.1 Jupiter); true size unknown.
Orbital
- Semi-major axis
- 20.9 AU
- From the NASA Exoplanet Archive (radial velocity; JWST-imaged 2024)
- Eccentricity
- 0.24
- From the NASA Exoplanet Archive (radial velocity; JWST-imaged 2024)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (radial velocity; JWST-imaged 2024)
- Orbital period
- 107.87 years
- From the NASA Exoplanet Archive (radial velocity; JWST-imaged 2024)
- Perihelion
- 15.9 AU
- Computed from the orbital elements
- Aphelion
- 25.9 AU
- Computed from the orbital elements
- Mean orbital velocity
- 5.77 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- A gas giant of roughly 7.6 Jupiter masses — its mass measured by astrometry and radial velocity. Imaged only as a faint thermal-infrared point by JWST; its visible appearance is unknown.
- Cloud appearance
- Appearance based on ESO/M. Kornmesser's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The banded clouds shown are a representation of its class, shown only in Visual mode; Realism shows a plain spectral colour.
Radiation & temperature
- Insolation
- 0.000547 S⊕ · 1/1,828 of the sunlight Earth receives
- Computed from Epsilon Indi's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 275 K (2 °C)
- Effective temperature measured by JWST (2024) — a genuinely cold giant, colder than any directly imaged before.
Discovery & history
- Discovered
- October 1, 2019
- By
- M. Feng et al.
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'Ab' as the first planet of Epsilon Indi A (distinguishing it from the distant brown-dwarf pair Epsilon Indi B).
Suspected from a slow drift in Epsilon Indi's radial velocity tracked since the early 2000s, and confirmed in 2024 when JWST captured its faint thermal glow - a genuinely cold giant planet, far colder than any previously imaged.
Images
No official imagery available — this object has never been visited and no officially-licensed depiction exists.