HD 219134 b
Planet· orbits HD 219134
HD 219134 b - the nearest transiting rocky planet known: a hot super-Earth (~4.7 Earth masses, ~1.6 Earth radii) orbiting every 3 days. Because it both transits and has a measured mass, its high, rocky density is genuinely known - though its glowing surface has never been directly seen.
Open in 3D viewSee HD 219134 b in the live, interactive 3D map
Key facts
Mass
2.83 × 10²⁵ kg
4.74 M⊕
Radius
10,206 km
1.6× wider than Earth
Surface gravity
18.1 m/s²
1.85× Earth's gravity
Year
3.09 Earth days
Distance from HD 219134
5,798,413 km
Science
Physical
- Mass
- 2.83 × 10²⁵ kg · 4.74 M⊕
- Radius
- 10,206 km · 1.6× wider than Earth
- Density
- 6,356 kg/m³ · 6.4× water
- Computed from mass and radius
- Surface gravity
- 18.1 m/s² · 1.85× Earth's gravity
- Computed from mass and radius
- Escape velocity
- 19.2 km/s · 1.72× Earth's escape velocity
- Computed from mass and radius
Orbital
- Semi-major axis
- 5,798,413 km
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Eccentricity
- 0
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Orbital period
- 3.1 days
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Perihelion
- 5,798,413 km
- Computed from the orbital elements
- Aphelion
- 5,798,413 km
- Computed from the orbital elements
- Mean orbital velocity
- 136 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- A rocky super-Earth of ~4.7 Earth masses and ~1.6 Earth radii — because it both transits and has a measured mass, its high (rocky) density is genuinely known. It is the nearest transiting rocky planet to the Sun; its glowing surface has never been directly imaged.
- Surface appearance
- Appearance based on ESO/M. Kornmesser's artist's concept. No spacecraft has imaged this world, so its real appearance is unknown — The surface shown is an artistic representation, shown only in Visual mode; Realism shows a plain spectral colour.
Radiation & temperature
- Insolation
- 176 S⊕ · 176× the sunlight Earth receives
- Computed from HD 219134's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 1,015 K (742 °C)
- Computed model value for its 3-day orbit — hot enough to bake rock; not a directly measured temperature.
Discovery & history
- Method
- Transit detection
- 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 by radial velocity in 2015 and caught transiting by Spitzer the same year, making it the closest transiting rocky planet to the Sun.
Images
Images from open archives · credit shown per image