Kepler-1690 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1690 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1690, located approximately 2295.5 light-years (703.79 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0893% across the stellar disk), this world measures 2.811 Earth radii and has a measured mass of 8.3 Earth masses. Combining its mass and radius yields a mean bulk density of 2.06 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.2 km/s.
In its orbital architecture around Kepler-1690, Kepler-1690 b completes one full revolution every 234.636 Earth days at a semi-major axis of 0.7097 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 32.9 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.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.811 R⊕, Kepler-1690 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star Kepler-1690 is classified as a stellar host with an effective photospheric temperature of 5,404 K, a radius of 0.8623 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.569 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.5 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, Kepler-1690 shines at apparent V-band magnitude 14.882 (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-1690 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,404 K |
| Stellar Radius | 0.8623 R☉ |
| Stellar Mass | 0.9400 M☉ |
| Bolometric Luminosity | 0.569 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 8.500 Gyr |
| Apparent Magnitude | V: 14.882 · G: 14.642 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.709700 AU |
| Orbital Period | 234.636 days |
| Mean Orbital Velocity | 32.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9900° |
| Mean Bulk Density | 2.06 g/cm³ (19.2 km/s vesc) |
| Insolation Flux | 1.2000 S⊕ (~1,633 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2295.500 LY (703.789 pc) |