Kepler-990 b
Astrophysical Synthesis & Habitability Characterization
Kepler-990 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-990, located approximately 2616.3 light-years (802.16 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0487% across the stellar disk), this world measures 2.6 Earth radii and has a measured mass of 7.27 Earth masses. Combining its mass and radius yields a mean bulk density of 2.28 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18.7 km/s.
In its orbital architecture around Kepler-990, Kepler-990 b completes one full revolution every 9.917 Earth days at a semi-major axis of 0.08595 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 94.3 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 903 K (+630°C / +1166°F) and receiving 108.30 S⊕ (~147,396 W/m²), Kepler-990 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-990 is classified as a stellar host with an effective photospheric temperature of 5,948 K, a radius of 1.08 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 1.31 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.55 Gyr and a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-990 shines at apparent V-band magnitude 14.716 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-990 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-990 b sharing its stellar neighborhood alongside Kepler-990 c.
Methodology: Computed using the Schulze-Makuch et al. (2011) weighted metric comparing physical interior (radius, estimated density) and surface thermal regime (escape velocity, equilibrium temperature).
Discovery Facility: Kepler · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-990 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,948 K |
| Stellar Radius | 1.0800 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 1.31 L☉ |
| Metallicity [Fe/H] | 0.010 dex |
| Stellar Age | 3.550 Gyr |
| Apparent Magnitude | V: 14.716 · G: 14.495 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.085950 AU |
| Orbital Period | 9.917 days |
| Mean Orbital Velocity | 94.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.0600° |
| Mean Bulk Density | 2.28 g/cm³ (18.7 km/s vesc) |
| Insolation Flux | 108.3000 S⊕ (~147,396 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2616.300 LY (802.163 pc) |