Kepler-1688 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1688 b is a confirmed super-earth exoplanet orbiting the star Kepler-1688, located approximately 1850.8 light-years (567.45 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0241% across the stellar disk), this world measures 1.262 Earth radii and has a measured mass of 2.13 Earth masses. Combining its mass and radius yields a mean bulk density of 5.84 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.34 g⊕ (13.14 m/s²), and an escape velocity of 14.5 km/s.
In its orbital architecture around Kepler-1688, Kepler-1688 b completes one full revolution every 5.62 Earth days at a semi-major axis of 0.0577 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 111.7 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 772 K (+499°C / +930°F) and receiving 84.01 S⊕ (~114,338 W/m²), Kepler-1688 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1688 is classified as a stellar host with an effective photospheric temperature of 4,632 K, a radius of 0.746 R☉, a mass of 0.814 M☉, an estimated bolometric luminosity of 0.23 L☉. Stellar evolution modeling indicates an estimated stellar age of 14 Gyr and a metallicity of [Fe/H] = -0.046 dex (near-solar heavy-element abundance). From Earth, Kepler-1688 shines at apparent V-band magnitude 14.142 (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-1688 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,632 K |
| Stellar Radius | 0.7460 R☉ |
| Stellar Mass | 0.8140 M☉ |
| Bolometric Luminosity | 0.23 L☉ |
| Metallicity [Fe/H] | -0.046 dex |
| Stellar Age | 14.000 Gyr |
| Apparent Magnitude | V: 14.142 · G: 13.986 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.057700 AU |
| Orbital Period | 5.62 days |
| Mean Orbital Velocity | 111.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 78.7200° |
| Mean Bulk Density | 5.84 g/cm³ (14.5 km/s vesc) |
| Insolation Flux | 84.0100 S⊕ (~114,338 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1850.800 LY (567.447 pc) |