GJ 1214

Star

GJ 1214 — a small, cool red dwarf only ~0.18 solar masses, ~48 light-years away in Ophiuchus. Faint and long-lived, it hosts one of the most-studied 'water worlds': the steamy sub-Neptune GJ 1214 b.

Open in 3D viewSee GJ 1214 in the live, interactive 3D map

Key facts

Mass

3.62 × 10²⁹ kg

0.182 M☉

Radius

150,271 km

22% of the Sun's radius

Surface temperature

3,101 K (2,828 °C)

Spectral type

M4V (a small red dwarf)

Science

Physical

Mass: 3.62 × 10²⁹ kg · 0.182 M☉
Radius: 150,271 km · 22% of the Sun's radius
Density: 25,467 kg/m³ · 25× water; Computed from mass and radius
Spectral type: M4V (a small red dwarf)

Motion through space

Proper motion: 0.948 arcseconds per year · its drift across our sky; SIMBAD — 2020yCat.1350....0G, 2022yCat.1355....0G
Radial velocity: +20.9 km/s · moving away from the Sun; SIMBAD — 2020yCat.1350....0G, 2022yCat.1355....0G
Speed across our line of sight: 65.8 km/s; Computed from proper motion and parallax
Speed through space, relative to the Sun: 69 km/s; Computed from proper motion, parallax and radial velocity

Composition

By mass: A cool red dwarf only ~0.18 solar masses, 48 light-years away in Ophiuchus.

Temperature

Surface: 3,101 K (2,828 °C)

Radiation & temperature

Luminosity: 1.49 × 10²⁴ W · 0.00389 L☉
Surface temperature: 3,101 K (2,828 °C)
Peak wavelength: 934 nm · near-infrared (mostly invisible to the eye); Computed (Wien's law) from the surface temperature

Discovery & history

Method: Telescope
Name: A Gliese-Jahreiß catalogue designation.

A nearby red dwarf whose 2009 transiting planet — close, and orbiting a small star — became a prime target for probing sub-Neptune atmospheres.

Images

Where to find it — in Ophiuchus, the Serpent-Bearer (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