Kepler-1669 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1669 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1669, located approximately 1772.5 light-years (543.44 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1274% across the stellar disk), this world measures 2.78 Earth radii and has a measured mass of 8.15 Earth masses. Combining its mass and radius yields a mean bulk density of 2.09 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-1669, Kepler-1669 b completes one full revolution every 9.512 Earth days at a semi-major axis of 0.0745 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 85.2 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 530 K (+257°C / +495°F) and receiving 18.66 S⊕ (~25,396 W/m²), Kepler-1669 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1669 is classified as a stellar host with an effective photospheric temperature of 4,303 K, a radius of 0.7141 R☉, a mass of 0.67 M☉, an estimated bolometric luminosity of 0.157 L☉. Stellar evolution modeling indicates an estimated stellar age of 13.9 Gyr and a metallicity of [Fe/H] = -0.23 dex (metal-poor relative to the Sun). From Earth, Kepler-1669 shines at apparent V-band magnitude 16.473 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-1669 system is a multi-planet architecture hosting 3 confirmed worlds, with Kepler-1669 b sharing its stellar neighborhood alongside Kepler-1669 c, Kepler-1669 d.
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-1669 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,303 K |
| Stellar Radius | 0.7141 R☉ |
| Stellar Mass | 0.6700 M☉ |
| Bolometric Luminosity | 0.157 L☉ |
| Metallicity [Fe/H] | -0.230 dex |
| Stellar Age | 13.900 Gyr |
| Apparent Magnitude | V: 16.473 · G: 15.909 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.074500 AU |
| Orbital Period | 9.512 days |
| Mean Orbital Velocity | 85.2 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.7000° |
| Mean Bulk Density | 2.09 g/cm³ (19.2 km/s vesc) |
| Insolation Flux | 18.6600 S⊕ (~25,396 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1772.500 LY (543.444 pc) |