Kepler-1989 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1989 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1989, located approximately 4083.9 light-years (1252.13 parsecs) from the Solar System. First announced in 2023 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1597% across the stellar disk), this world measures 4.62 Earth radii (0.41 Jupiter radii) and has a measured mass of 19.3 Earth masses. Combining its mass and radius yields a mean bulk density of 1.08 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 22.9 km/s.
In its orbital architecture around Kepler-1989, Kepler-1989 b completes one full revolution every 10.161 Earth days at a semi-major axis of 0.0918 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 98.3 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 904 K (+631°C / +1168°F) and receiving 157.97 S⊕ (~214,997 W/m²), Kepler-1989 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1989 is classified as a stellar host with an effective photospheric temperature of 6,032 K, a radius of 1.06 R☉, a mass of 0.999 M☉, an estimated bolometric luminosity of 1.335 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.14 dex (metal-poor relative to the Sun). From Earth, Kepler-1989 shines at apparent V-band magnitude 14.289 (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-1989 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,032 K |
| Stellar Radius | 1.0600 R☉ |
| Stellar Mass | 0.9990 M☉ |
| Bolometric Luminosity | 1.335 L☉ |
| Metallicity [Fe/H] | -0.140 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 14.289 · G: 14.613 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.091800 AU |
| Orbital Period | 10.161 days |
| Mean Orbital Velocity | 98.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.7800° |
| Mean Bulk Density | 1.08 g/cm³ (22.9 km/s vesc) |
| Insolation Flux | 157.9700 S⊕ (~214,997 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4083.900 LY (1252.130 pc) |