Gliese 436

Star

Gliese 436 - a red dwarf 31.9 light-years away in Leo, host to one of the best-studied warm Neptunes known. Its planet transits, so we have measured its size and density directly, and it has an odd, tilted, very eccentric orbit that hints at an unseen sculptor.

Open in 3D viewSee Gliese 436 in the live, interactive 3D map

Key facts

Mass

9.35 × 10²⁹ kg

0.47 M☉

Radius

316,544 km

46% of the Sun's radius

Surface temperature

3,586 K (3313 °C)

Luminosity

9.95 × 10²⁴ W

Spectral type

M2.5V (red dwarf)

Science

Physical

Mass: 9.35 × 10²⁹ kg · 0.47 M☉
Radius: 316,544 km · 46% of the Sun's radius
Density: 7,036 kg/m³ · 7× water
Spectral type: M2.5V (red dwarf)

Rotation

Note: Slow rotation (tens of days); a quiet star, well suited to precise planet studies.

Composition

By mass: A hydrogen/helium red dwarf about half the Sun's mass and a few percent of its light. Its steadiness let astronomers measure the tiny transit of its Neptune-sized planet and track the planet's escaping atmosphere.

Temperature

Surface: 3,586 K (3313 °C)

Radiation & temperature

Luminosity: 9.95 × 10²⁴ W · 0.026 L☉
Surface temperature: 3,586 K (3313 °C)
Peak wavelength: 808 nm · near-infrared (mostly invisible to the eye)

Discovery & history

Name: A catalogue designation (Gliese 436); the star has no proper name.

The planet's radial-velocity wobble was found in 2004; in 2007 it was caught transiting, making it the first confirmed Neptune-sized transiting planet and a benchmark for the study of small-planet atmospheres.

Images

Where to find it — in Leo, the Lion (IAU constellation chart). To the eye it is a single point of light; no telescope has imaged its surface. — IAU / Sky & Telescope, R. Sinnott & R. Fienberg (CC BY 3.0) · Wikimedia Commons

Images from open archives · credit shown per image