Kepler-186

Star

Kepler-186 — a red dwarf about half the Sun's mass, ~580 light-years away in Cygnus. It hosts four confirmed Earth-to-super-Earth planets on tight orbits, and is famous as the proposed home of the first Earth-size habitable-zone planet — a claim now under debate.

Open in 3D viewSee Kepler-186 in the live, interactive 3D map

Key facts

Mass

9.51 × 10²⁹ kg

0.478 M☉

Radius

328,370 km

47% of the Sun's radius

Surface temperature

3,788 K (3,515 °C)

Luminosity

1.58 × 10²⁵ W

Spectral type

M1 (red dwarf)

Science

Physical

Mass: 9.51 × 10²⁹ kg · 0.478 M☉
Radius: 328,370 km · 47% of the Sun's radius
Density: 6,410 kg/m³ · 6.4× water; Computed from mass and radius
Spectral type: M1 (red dwarf)

Motion through space

Proper motion: 0.00487 arcseconds per year · its drift across our sky; SIMBAD — 2020yCat.1350....0G, 2020AJ....160..120J
Radial velocity: -62.0 km/s · approaching the Sun; SIMBAD — 2020yCat.1350....0G, 2020AJ....160..120J
Speed across our line of sight: 4.1 km/s; Computed from proper motion and parallax
Speed through space, relative to the Sun: 62.2 km/s; Computed from proper motion, parallax and radial velocity

Rotation

Note: A faint, distant red dwarf; only its transiting planets' shadows made it measurable at all.

Composition

By mass: A hydrogen/helium red dwarf about half the Sun's mass, ~580 light-years away. It hosts four confirmed Earth-to-super-Earth planets on tight orbits, and is famous as the proposed home of the first Earth-size habitable-zone planet — a claim now under debate.

Temperature

Surface: 3,788 K (3,515 °C)

Radiation & temperature

Luminosity: 1.58 × 10²⁵ W · 0.0413 L☉
Surface temperature: 3,788 K (3,515 °C)
Peak wavelength: 765 nm · near-infrared (mostly invisible to the eye); Computed (Wien's law) from the surface temperature

Discovery & history

Method: Telescope
Name: A Kepler-mission catalogue designation; no proper name.

Found by NASA's Kepler telescope in 2014, this faint, distant red dwarf became one of the mission's most celebrated systems for the (now-contested) habitable-zone planet f announced alongside its four secure inner worlds.

Images

NASA's comparison of Kepler's small habitable-zone planets — including Kepler-186 f and Kepler-442 b — with the Solar System (a NASA diagram). — NASA/Ames/JPL-Caltech (public domain) · Wikimedia Commons

Where to find it — in Cygnus, the Swan (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