Gliese 876
Star
Gliese 876 - a red dwarf 15.2 light-years away in Aquarius, and a landmark of exoplanet science: in 1998 it became the FIRST red dwarf found to host a planet. Four planets are now known, three of them locked in a Laplace resonance (their orbital periods in a 1:2:4 ratio) - the first such chain found beyond the Solar System.
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Key facts
Mass
6.36 × 10²⁹ kg
0.32 M☉
Radius
208,710 km
30% of the Sun's radius
Surface temperature
3,294 K (3021 °C)
Luminosity
4.75 × 10²⁴ W
Spectral type
M3.5V (red dwarf)
Science
Physical
- Mass
- 6.36 × 10²⁹ kg · 0.32 M☉
- Radius
- 208,710 km · 30% of the Sun's radius
- Density
- 16,713 kg/m³ · 17× water
- Spectral type
- M3.5V (red dwarf)
Rotation
- Note
- Rotates roughly once every 87 days; relatively quiet, aiding the precise radial-velocity work that mapped its planets.
Composition
- By mass
- A small hydrogen/helium red dwarf about a third of the Sun's mass and barely 1% of its light. Cool and long-lived, it is the kind of star most planets in the Galaxy orbit — which is why finding its four-planet resonant family was so influential.
Temperature
- Surface
- 3,294 K (3021 °C)
Radiation & temperature
- Luminosity
- 4.75 × 10²⁴ W · 0.0124 L☉
- Surface temperature
- 3,294 K (3021 °C)
- Peak wavelength
- 880 nm · near-infrared (mostly invisible to the eye)
Discovery & history
- Name
- A catalogue designation (Gliese 876); the star also carries the variable-star name IL Aquarii.
In 1998 two teams independently detected a giant planet tugging on this nearby red dwarf - the first planet known around an M dwarf, the commonest kind of star. Follow-up with Keck and ESO's HARPS revealed three more and the elegant resonant lock of the outer three, a natural laboratory for planet dynamics.
Images
Images from open archives · credit shown per image