Kepler-1789 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1789 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1789, located approximately 1994.3 light-years (611.46 parsecs) from the Solar System. First announced in 2021 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0854% across the stellar disk), this world measures 2.831 Earth radii and has a measured mass of 8.4 Earth masses. Combining its mass and radius yields a mean bulk density of 2.04 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 19.3 km/s.
In its orbital architecture around Kepler-1789, Kepler-1789 b completes one full revolution every 80.232 Earth days at a semi-major axis of 0.3543 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 48 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 380 K (+107°C / +225°F) and receiving 4.91 S⊕ (~6,683 W/m²), Kepler-1789 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1789 is classified as a stellar host with an effective photospheric temperature of 5,436 K, a radius of 0.888 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 0.618 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.5 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, Kepler-1789 shines at apparent V-band magnitude 14.449 (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-1789 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,436 K |
| Stellar Radius | 0.8880 R☉ |
| Stellar Mass | 0.9200 M☉ |
| Bolometric Luminosity | 0.618 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 4.500 Gyr |
| Apparent Magnitude | V: 14.449 · G: 14.316 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.354300 AU |
| Orbital Period | 80.232 days |
| Mean Orbital Velocity | 48 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.1900° |
| Mean Bulk Density | 2.04 g/cm³ (19.3 km/s vesc) |
| Insolation Flux | 4.9100 S⊕ (~6,683 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1994.300 LY (611.461 pc) |