55 Cancri b
Planet· orbits 55 Cancri
55 Cancri b - the second planet out, a warm gas giant of about 0.8 Jupiter masses on a 15-day orbit; the first planet found in this system. Its true mass is known, but it has never transited, so its size is model-based. Never imaged.
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Key facts
Mass
1.58 × 10²⁷ kg
0.831 M♃ (264 M⊕)
Year
14.65 Earth days
Distance from 55 Cancri
0.118 AU
Science
Physical
- Mass
- 1.58 × 10²⁷ kg · 0.831 M♃ (264 M⊕)
- Radius
- Not measured
- No transit — radius is a model estimate for a ~0.8-Jupiter gas giant; no density is quoted.
Orbital
- Semi-major axis
- 0.118 AU
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Eccentricity
- 0.003
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Orbital period
- 14.7 days
- From the NASA Exoplanet Archive (radial-velocity orbit)
- Perihelion
- 0.118 AU
- Computed from the orbital elements
- Aphelion
- 0.118 AU
- Computed from the orbital elements
- Mean orbital velocity
- 87.6 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- A warm gas giant of true mass ~0.8 Jupiter — hydrogen and helium; one of the earliest exoplanets found (1996). Never imaged.
- 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
- 45.6 S⊕ · 45.6× the sunlight Earth receives
- Computed from 55 Cancri's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 700 K (427 °C)
- Computed model value for its 15-day orbit — not measured.
Discovery & history
- Method
- Radial-velocity detection (stellar wobble)
- Name
- Designated 'b' under the IAU convention that letters a star's planets 'b', 'c', 'd'... in the order they are discovered (the star itself is the unwritten 'a').
Found in 1996 - one of the earliest exoplanets ever discovered, and the seed of what became a five-planet system.
Images
No official imagery available — this object has never been visited and no officially-licensed depiction exists.