Kepler-1581 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1581 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1581, located approximately 1608.5 light-years (493.18 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0036% across the stellar disk), this world measures 0.8 Earth radii and has a measured mass of 0.437 Earth masses. Combining its mass and radius yields a mean bulk density of 4.71 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 0.68 g⊕ (6.67 m/s²), and an escape velocity of 8.3 km/s.

In its orbital architecture around Kepler-1581, Kepler-1581 b completes one full revolution every 6.284 Earth days at a semi-major axis of 0.06865 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 118.9 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 1108 K (+835°C / +1535°F) and receiving 470.86 S⊕ (~640,843 W/m²), Kepler-1581 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1581 is classified as a stellar host with an effective photospheric temperature of 6,022 K, a radius of 1.23 R☉, a mass of 1.12 M☉, an estimated bolometric luminosity of 1.785 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.17 Gyr and a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, Kepler-1581 shines at apparent V-band magnitude 12.442 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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