Kepler-1855 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1855 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1855. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0981% across the stellar disk), this world measures 1.216 Earth radii and has a measured mass of 1.96 Earth masses. Combining its mass and radius yields a mean bulk density of 6.01 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.33 g⊕ (13.04 m/s²), and an escape velocity of 14.2 km/s.

In its orbital architecture around Kepler-1855, Kepler-1855 b completes one full revolution every 0.727 Earth days at a semi-major axis of 0.0115 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 172 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 849 K (+576°C / +1069°F) and receiving 86.97 S⊕ (~118,366 W/m²), Kepler-1855 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1855 is classified as a stellar host with an effective photospheric temperature of 3,460 K, a radius of 0.356 R☉, a mass of 0.385 M☉, an estimated bolometric luminosity of 0.016 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.85 Gyr and a metallicity of [Fe/H] = 0.07 dex (metal-rich relative to the Sun). From Earth, Kepler-1855 shines at apparent V-band magnitude 16.556 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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