13point8100 ly map
2 known planets · 49.6 light years

GJ 317

GJ 317 is a red dwarf (M3.5 V) 49.6 light years away, with 2 confirmed planets. Distances and orbital speeds are to scale; the star and planets are enlarged so you can see them.

Day 0
habitable zone (estimate)planet orbits

Green band: where liquid water could exist on a planet's surface. Drag to turn the system, pinch or scroll to zoom.

The star

The star

GJ 317

Type
M3.5 V
Surface
≈ 3,496 K
Size
0.40 × the Sun
Mass
0.40 × the Sun
Brightness
0.0206 × the Sun
Habitable zone
0.117–0.305 AU

The planets

GJ 317

GJ 317 b

Year
695.69 days
Distance from star
1.14 AU
Mass
2.5 Jupiters
Size
13 × Earth
Temperature
≈ 100 K (-173 °C)
Found
2007, radial velocity (W. M. Keck Observatory)
Outside the habitable zone
GJ 317

GJ 317 c

Year
17.8 years
Distance from star
5.04 AU
Mass
at least 1.4 Jupiters
Size
14 × Earth
Temperature
≈ 48 K (-225 °C)
Found
2016, radial velocity (W. M. Keck Observatory)
Outside the habitable zone

Masses found by the wobble method are minimums, because the orbit's tilt is unknown. Temperatures are equilibrium estimates for a bare planet, before any atmosphere.

How we know

The wobble

The planet tugs its star back and forth. Spectrographs measure the tiny shift in the star's light, which gives the planet's year and a minimum mass.

Sources

  1. Planet and star parameters: NASA Exoplanet Archive, Planetary Systems Composite Parameters, retrieved 31 Oct 2026. This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with NASA under the Exoplanet Exploration Program.
  2. Position: HYG Database v4.1 (CC BY-SA 4.0).
  3. Habitable zone: a simple estimate from the star's brightness (√L × 0.95 to 1.67 AU), shown as a guide.
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