Kepler-690 b
Astrophysical Synthesis & Habitability Characterization
Kepler-690 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-690, located approximately 5431.5 light-years (1665.31 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.2211% across the stellar disk), this world measures 5.95 Earth radii (0.53 Jupiter radii) and has a measured mass of 29.6 Earth masses. Combining its mass and radius yields a mean bulk density of 0.77 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.84 g⊕ (8.24 m/s²), and an escape velocity of 24.9 km/s.
In its orbital architecture around Kepler-690, Kepler-690 b completes one full revolution every 7.748 Earth days at a semi-major axis of 0.081 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 113.7 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 964 K (+691°C / +1276°F) and receiving 225.70 S⊕ (~307,179 W/m²), Kepler-690 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-690 is classified as a stellar host with an effective photospheric temperature of 5,913 K, a radius of 1.16 R☉, a mass of 1.11 M☉, an estimated bolometric luminosity of 1.476 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.55 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, Kepler-690 shines at apparent V-band magnitude 15.701 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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-690 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,913 K |
| Stellar Radius | 1.1600 R☉ |
| Stellar Mass | 1.1100 M☉ |
| Bolometric Luminosity | 1.476 L☉ |
| Metallicity [Fe/H] | 0.190 dex |
| Stellar Age | 3.550 Gyr |
| Apparent Magnitude | V: 15.701 · G: 15.672 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.081000 AU |
| Orbital Period | 7.748 days |
| Mean Orbital Velocity | 113.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.0200° |
| Mean Bulk Density | 0.77 g/cm³ (24.9 km/s vesc) |
| Insolation Flux | 225.7010 S⊕ (~307,179 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 5431.500 LY (1665.310 pc) |