NASA (Exoplanet Catalog artwork)Barnard's Star b
A sub-Earth around the second-closest star system, confirmed after a false start
Overview
Barnard's Star b, or Barnard b, is a sub-Earth-mass exoplanet closely orbiting Barnard's Star, a nearby red dwarf star six light-years from Earth. The planet was discovered using radial velocity observations from the ESPRESSO spectrograph on the Very Large Telescope, and was announced on 1 October 2024. It is the second from its star of four known planets in its system.
Source: Wikipedia
NASA: Barnard b is a terrestrial exoplanet that orbits a M-type star. Its mass is 0.299 Earths, it takes 3.2 days to complete one orbit of its star, and is 0.0229 AU from its star. Its discovery was announced in 2024.
Why it matters
- A 2018 super-Earth claim was refuted; ESPRESSO confirmed a different, smaller planet in 2024.
- Roughly a third of Earth's mass on a 3.15-day orbit, too hot for liquid water.
- Three more small planets were confirmed in 2025, making Barnard's Star a compact four-planet system.
Discovery & system
- Discovered
- 2024 · Radial Velocity · Paranal Observatory
- Discovery paper
- González Hernández et al. 2024
- Host star
- Barnard's star · M3.5-4 V · 3,195 K · 0.16 M☉
- System
- 4 known planets
- Siblings
- Barnard d, Barnard c, Barnard e
The system
| World | Period | Distance | Radius | Mass | Temp. |
|---|---|---|---|---|---|
| Barnard d | 2.34 d | 0.019 AU | 0.69 R⊕ | ≥ 0.26 M⊕ | 483 K |
| Barnard b | 3.15 d | 0.023 AU | 0.72 R⊕ | ≥ 0.3 M⊕ | 438 K |
| Barnard c | 4.12 d | 0.027 AU | 0.74 R⊕ | ≥ 0.34 M⊕ | 400 K |
| Barnard e | 6.74 d | 0.038 AU | 0.64 R⊕ | ≥ 0.19 M⊕ | 340 K |
By the numbers
- Radius
- 0.72 R⊕4,587 km
- Mass
- ≥ 0.3 M⊕1.79 ×10²⁴ kg · minimum mass (M sin i)
- Orbital period
- 3.15 d0.01 yr
- Distance from star
- 0.023 AU3.43 million km
- Eccentricity
- 0.03nearly circular
- Equilibrium temp.
- 438 K165 °C
- Starlight received
- 7 × Earth
- Distance from Earth
- 6 ly1.8 pc
- Density
- 4.4 g/cm³0.8 × Earth
Sources
Image: NASA (Exoplanet Catalog artwork) · NASA media: generally free of copyright · image page
Text: Wikipedia (CC BY-SA 4.0). Taglines and highlights are editorial.