Gliese 876 is a red dwarf in Aquarius, the first red dwarf found to have a planet, and now known to host a family of planets locked in step.
At a glance
| type | red dwarf (class M) |
|---|---|
| distance from the Sun | 15.3 light-years (4.68 pc) |
| its light left it | 15.3 years ago |
| luminosity | 0.0122 × the Sun |
| radius | 0.38 × the Sun |
| surface temperature | 3,130 K |
Read off the piece’s own catalogue, the same values it draws with.
About Gliese 876
Gliese 876 is a small, cool star, invisible without a telescope. When planets around Sun-like stars were first being found, it showed that red dwarfs, the commonest stars in the Galaxy, could have planets too: a giant planet more massive than Jupiter, detected by the wobble it gave its star.
More planets followed, found the same way. Several of them are in resonance: their orbital periods lock together in simple whole-number ratios, so they pass one another at the same points again and again and their mutual pulls are strong enough to be measured. This let astronomers weigh the planets far more precisely than for most systems found by the wobble method.
What you see in the piece
From Earth it lies below the naked-eye limit in the piece. Fly to it and it is a dim orange-red disc.
Measured or modelled
The exact number of planets and the masses of the smallest ones depend on how the radial-velocity data are modelled, and have been revised as more measurements came in.
Questions
Why is Gliese 876 famous?
It was the first red dwarf found to have a planet, and its planets are locked in orbital resonance, which made it a key system for understanding how planetary orbits interact.