Kepler-1727 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1727 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1727, located approximately 2916.4 light-years (894.19 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1259% across the stellar disk), this world measures 3.173 Earth radii (0.28 Jupiter radii) and has a measured mass of 10.2 Earth masses. Combining its mass and radius yields a mean bulk density of 1.76 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.01 g⊕ (9.9 m/s²), and an escape velocity of 20.1 km/s.

In its orbital architecture around Kepler-1727, Kepler-1727 b completes one full revolution every 9.029 Earth days at a semi-major axis of 0.0796 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 95.9 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 757 K (+484°C / +903°F) and receiving 77.75 S⊕ (~105,818 W/m²), Kepler-1727 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1727 is classified as a stellar host with an effective photospheric temperature of 5,349 K, a radius of 0.82 R☉, a mass of 0.824 M☉, an estimated bolometric luminosity of 0.494 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.7 Gyr and a metallicity of [Fe/H] = -0.12 dex (metal-poor relative to the Sun). From Earth, Kepler-1727 shines at apparent V-band magnitude 15.751 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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