Kepler-1906 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1906 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1906, located approximately 4437.8 light-years (1360.63 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.081% across the stellar disk), this world measures 2.776 Earth radii and has a measured mass of 8.13 Earth masses. Combining its mass and radius yields a mean bulk density of 2.1 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.1 km/s.

In its orbital architecture around Kepler-1906, Kepler-1906 b completes one full revolution every 7.363 Earth days at a semi-major axis of 0.0738 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 109 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 901 K (+628°C / +1162°F) and receiving 155.72 S⊕ (~211,935 W/m²), Kepler-1906 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1906 is classified as a stellar host with an effective photospheric temperature of 5,868 K, a radius of 0.894 R☉, a mass of 0.987 M☉, an estimated bolometric luminosity of 0.85 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.5 Gyr and a metallicity of [Fe/H] = -0.12 dex (metal-poor relative to the Sun). From Earth, Kepler-1906 shines at apparent V-band magnitude 15.322 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).