Kepler-439 b
Astrophysical Synthesis & Habitability Characterization
Kepler-439 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-439, located approximately 2469.2 light-years (757.05 parsecs) from the Solar System. First announced in 2015 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0562% across the stellar disk), this world measures 2.24 Earth radii and has a measured mass of 5.65 Earth masses. Combining its mass and radius yields a mean bulk density of 2.77 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around Kepler-439, Kepler-439 b completes one full revolution every 178.14 Earth days at a semi-major axis of 0.563 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 34.4 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.03 (ranging from 0.5461 AU at periapsis to 0.5799 AU at apoapsis), the planet experiences minimal orbital distance variation.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.240 R⊕, Kepler-439 b 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-439 is classified as a stellar host with an effective photospheric temperature of 5,431 K, a radius of 0.866 R☉, a mass of 0.884 M☉, an estimated bolometric luminosity of 0.585 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.2 Gyr and a metallicity of [Fe/H] = 0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-439 shines at apparent V-band magnitude 14.654 (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-439 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,431 K |
| Stellar Radius | 0.8660 R☉ |
| Stellar Mass | 0.8840 M☉ |
| Bolometric Luminosity | 0.585 L☉ |
| Metallicity [Fe/H] | 0.020 dex |
| Stellar Age | 7.200 Gyr |
| Apparent Magnitude | V: 14.654 · G: 14.545 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.563000 AU |
| Orbital Period | 178.14 days |
| Mean Orbital Velocity | 34.4 km/s |
| Orbital Eccentricity (e) | 0.03000 |
| Orbital Inclination (i) | 89.9500° |
| Mean Bulk Density | 2.77 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 1.8300 S⊕ (~2,491 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2469.200 LY (757.048 pc) |