Kepler-987 b

Astrophysical Synthesis & Habitability Characterization

Kepler-987 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-987, located approximately 2981.5 light-years (914.13 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1079% across the stellar disk), this world measures 3.26 Earth radii (0.29 Jupiter radii) and has a measured mass of 10.7 Earth masses. Combining its mass and radius yields a mean bulk density of 1.7 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 20.3 km/s.

In its orbital architecture around Kepler-987, Kepler-987 b completes one full revolution every 105.303 Earth days at a semi-major axis of 0.4238 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 43.8 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 351 K (+78°C / +172°F) and receiving 3.85 S⊕ (~5,244 W/m²), Kepler-987 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-987 is classified as a stellar host with an effective photospheric temperature of 5,637 K, a radius of 0.91 R☉, a mass of 0.97 M☉, an estimated bolometric luminosity of 0.75 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.45 Gyr and a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-987 shines at apparent V-band magnitude 15.171 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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