Kepler-1872 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1872 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1872, located approximately 2740.3 light-years (840.18 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.061% across the stellar disk), this world measures 2.384 Earth radii and has a measured mass of 6.28 Earth masses. Combining its mass and radius yields a mean bulk density of 2.56 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.2 km/s.

In its orbital architecture around Kepler-1872, Kepler-1872 b completes one full revolution every 3.826 Earth days at a semi-major axis of 0.0465 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 132.2 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 1005 K (+732°C / +1350°F) and receiving 241.25 S⊕ (~328,341 W/m²), Kepler-1872 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1872 is classified as a stellar host with an effective photospheric temperature of 5,223 K, a radius of 0.885 R☉, a mass of 0.913 M☉, an estimated bolometric luminosity of 0.523 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.32 dex (metal-rich relative to the Sun). From Earth, Kepler-1872 shines at apparent V-band magnitude 15.966 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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