YZ Ceti

Star

YZ Ceti - a small red flare star 12.1 light-years away in Cetus, host to three of the lowest-mass planets known, all packed inside a 5-day span. One of the nearest compact multi-planet systems.

Open in 3D viewSee YZ Ceti in the live, interactive 3D map

Key facts

Mass

2.82 × 10²⁹ kg

0.142 M☉

Radius

109,225 km

16% of the Sun's radius

Surface temperature

3,151 K (2878 °C)

Luminosity

8.42 × 10²³ W

Spectral type

M4.5V (red dwarf)

Science

Physical

Mass: 2.82 × 10²⁹ kg · 0.142 M☉
Radius: 109,225 km · 16% of the Sun's radius
Density: 51,743 kg/m³ · 52× water
Spectral type: M4.5V (red dwarf)

Composition

By mass: A red dwarf about 14% of the Sun's mass; a flare star that brightens abruptly.

Temperature

Surface: 3,151 K (2878 °C)

Radiation & temperature

Luminosity: 8.42 × 10²³ W · 0.0022 L☉
Surface temperature: 3,151 K (2878 °C)
Peak wavelength: 920 nm · near-infrared (mostly invisible to the eye)

Discovery & history

Name: Named for its variable-star designation YZ Ceti (a flare star in Cetus); also GJ 54.1.

A long-known flare star; in 2017 ESO's HARPS revealed three small planets, among the least-massive ever found by the radial-velocity method.

Images

Where to find it — in Cetus, the Sea Monster (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