Kepler-988 b

Astrophysical Synthesis & Habitability Characterization

Kepler-988 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-988, located approximately 994.4 light-years (304.89 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1282% across the stellar disk), this world measures 2.07 Earth radii and has a measured mass of 4.94 Earth masses. Combining its mass and radius yields a mean bulk density of 3.07 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.15 g⊕ (11.28 m/s²), and an escape velocity of 17.3 km/s.

In its orbital architecture around Kepler-988, Kepler-988 b completes one full revolution every 17.761 Earth days at a semi-major axis of 0.1085 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 66.5 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 368 K (+95°C / +203°F) and receiving 6.56 S⊕ (~8,928 W/m²), Kepler-988 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star Kepler-988 is classified as a stellar host with an effective photospheric temperature of 4,005 K, a radius of 0.53 R☉, a mass of 0.55 M☉, an estimated bolometric luminosity of 0.065 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.16 Gyr and a metallicity of [Fe/H] = -0.32 dex (metal-poor relative to the Sun). From Earth, Kepler-988 shines at apparent V-band magnitude 15.578 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.

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