Kepler-1698 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1698 b is a confirmed terrestrial exoplanet orbiting the star Kepler-1698, located approximately 725.2 light-years (222.35 parsecs) from the Solar System. First announced in 2020 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0176% across the stellar disk), this world measures 1.073 Earth radii and has a measured mass of 1.25 Earth masses. Combining its mass and radius yields a mean bulk density of 5.58 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 12.1 km/s.
In its orbital architecture around Kepler-1698, Kepler-1698 b completes one full revolution every 1.211 Earth days at a semi-major axis of 0.02065 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 185.6 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 1351 K (+1078°C / +1972°F) and receiving 697.60 S⊕ (~949,434 W/m²), Kepler-1698 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1698 is classified as a stellar host with an effective photospheric temperature of 4,975 K, a radius of 0.7417 R☉, a mass of 0.822 M☉, an estimated bolometric luminosity of 0.302 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.66 Gyr and a metallicity of [Fe/H] = 0.08 dex (metal-rich relative to the Sun). From Earth, Kepler-1698 shines at apparent V-band magnitude 13.054 (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-1698 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,975 K |
| Stellar Radius | 0.7417 R☉ |
| Stellar Mass | 0.8220 M☉ |
| Bolometric Luminosity | 0.302 L☉ |
| Metallicity [Fe/H] | 0.080 dex |
| Stellar Age | 1.660 Gyr |
| Apparent Magnitude | V: 13.054 · G: 12.876 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.020650 AU |
| Orbital Period | 1.211 days |
| Mean Orbital Velocity | 185.6 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 83.5600° |
| Mean Bulk Density | 5.58 g/cm³ (12.1 km/s vesc) |
| Insolation Flux | 697.6000 S⊕ (~949,434 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 725.200 LY (222.345 pc) |