Kepler-289 e
Astrophysical Synthesis & Habitability Characterization
Kepler-289 e is a confirmed sub-neptune exoplanet orbiting the star Kepler-289, located approximately 2297.6 light-years (704.44 parsecs) from the Solar System. First announced in 2025 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0749% across the stellar disk), this world measures 2.94 Earth radii and has a measured mass of 17.4 Earth masses. Combining its mass and radius yields a mean bulk density of 3.78 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 2.01 g⊕ (19.71 m/s²), and an escape velocity of 27.2 km/s.
In its orbital architecture around Kepler-289, Kepler-289 e completes one full revolution every 330.072 Earth days at a semi-major axis of 0.9342 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 30.8 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.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.940 R⊕, Kepler-289 e exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star Kepler-289 is classified as a stellar host with an effective photospheric temperature of 5,990 K, a radius of 0.985 R☉, a mass of 1.061 M☉, an estimated bolometric luminosity of 1.121 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.65 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-289 shines at apparent V-band magnitude 14.142 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-289 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-289 e sharing its stellar neighborhood alongside Kepler-289 b, Kepler-289 d, Kepler-289 c.
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-289 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,990 K |
| Stellar Radius | 0.9850 R☉ |
| Stellar Mass | 1.0610 M☉ |
| Bolometric Luminosity | 1.121 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 0.650 Gyr |
| Apparent Magnitude | V: 14.142 · G: 13.963 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.934200 AU |
| Orbital Period | 330.072 days |
| Mean Orbital Velocity | 30.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9100° |
| Mean Bulk Density | 3.78 g/cm³ (27.2 km/s vesc) |
| Insolation Flux | 1.5800 S⊕ (~2,150 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2297.600 LY (704.438 pc) |