L 98-59 b
Planet· orbits L 98-59
L 98-59 b - a transiting sub-Earth: at about half Earth's mass (~0.46 Earth) and 0.84 Earth radii, one of the smallest exoplanets ever weighed. Its transit and measured mass give a real density (rocky). Its hot surface has never been seen.
Open in 3D viewSee L 98-59 b in the live, interactive 3D map
Key facts
Mass
2.75 × 10²⁴ kg
0.46 M⊕
Radius
5,333 km
84% of Earth's radius
Surface gravity
6.45 m/s²
66% of Earth's gravity
Year
2.25 Earth days
Distance from L 98-59
3,336,033 km
Science
Physical
- Mass
- 2.75 × 10²⁴ kg · 0.46 M⊕
- Radius
- 5,333 km · 84% of Earth's radius
- Density
- 4,325 kg/m³ · 4.3× water
- Computed from mass and radius
- Surface gravity
- 6.45 m/s² · 66% of Earth's gravity
- Computed from mass and radius
- Escape velocity
- 8.29 km/s · 74% of Earth's escape velocity
- Computed from mass and radius
Orbital
- Semi-major axis
- 3,336,033 km
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Eccentricity
- 0.031
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Inclination
- 0.00 °
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Orbital period
- 2.3 days
- From the NASA Exoplanet Archive (transit + radial-velocity orbit)
- Perihelion
- 3,232,616 km
- Computed from the orbital elements
- Aphelion
- 3,439,450 km
- Computed from the orbital elements
- Mean orbital velocity
- 108 km/s
- Computed from the orbital elements
Composition
- Bulk composition
- A rocky sub-Earth of ~0.46 Earth masses and ~0.84 Earth radii — because it transits and has a measured mass, its density is genuinely known. At about half Earth's mass it is one of the smallest exoplanets ever weighed; its hot surface has never been 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
- 24.5 S⊕ · 24.5× the sunlight Earth receives
- Computed from L 98-59's luminosity and the orbital distance (inverse-square; Earth's sunlight = 1).
- Equilibrium temperature
- 620 K (347 °C)
- Computed model value for its 2.25-day orbit — hot; 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 transiting by TESS in 2019 and later weighed by ESPRESSO - a record small, measured rocky world.
Images
Images from open archives · credit shown per image