Kepler-1791 b

Astrophysical Synthesis & Habitability Characterization

Kepler-1791 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1791, located approximately 1964.2 light-years (602.22 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0591% across the stellar disk), this world measures 3.121 Earth radii (0.28 Jupiter radii) and has a measured mass of 9.91 Earth masses. Combining its mass and radius yields a mean bulk density of 1.8 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.02 g⊕ (10 m/s²), and an escape velocity of 19.9 km/s.

In its orbital architecture around Kepler-1791, Kepler-1791 b completes one full revolution every 7.721 Earth days at a semi-major axis of 0.0761 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 107.2 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 1021 K (+748°C / +1378°F) and receiving 257.14 S⊕ (~349,968 W/m²), Kepler-1791 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-1791 is classified as a stellar host with an effective photospheric temperature of 5,887 K, a radius of 1.177 R☉, a mass of 0.985 M☉, an estimated bolometric luminosity of 1.493 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.73 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, Kepler-1791 shines at apparent V-band magnitude 13.529 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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