Kepler-139 e
Astrophysical Synthesis & Habitability Characterization
Kepler-139 e is a confirmed gas giant exoplanet orbiting the star Kepler-139, located approximately 1275.4 light-years (391.04 parsecs) from the Solar System. First announced in 2023 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.7 Earth radii (1.22 Jupiter radii) and has a measured mass of 378 Earth masses (1.19 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.81 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.01 g⊕ (19.71 m/s²), and an escape velocity of 58.8 km/s.
In its orbital architecture around Kepler-139, Kepler-139 e completes one full revolution every 2047.635 Earth days (5.61Julian years) at a semi-major axis of 3.235796 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 17.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.01312 (ranging from 3.1933 AU at periapsis to 3.2782 AU at apoapsis), the planet experiences minimal orbital distance variation.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 154 K (-119°C / -182°F) and an incident flux of 0.10 S⊕ (~135 W/m²), surface water and volatile species on Kepler-139 e would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star Kepler-139 is classified as a stellar host with an effective photospheric temperature of 5,622 K, a radius of 1.045 R☉, a mass of 1.078 M☉, an estimated bolometric luminosity of 0.979 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.1 Gyr and a metallicity of [Fe/H] = 0.35 dex (metal-rich relative to the Sun). From Earth, Kepler-139 shines at apparent V-band magnitude 12.775 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-139 system is a multi-planet architecture hosting 5 confirmed worlds, with Kepler-139 e sharing its stellar neighborhood alongside Kepler-139 d, Kepler-139 b, Kepler-139 c, Kepler-139 f.
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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-139 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,622 K |
| Stellar Radius | 1.0450 R☉ |
| Stellar Mass | 1.0780 M☉ |
| Bolometric Luminosity | 0.979 L☉ |
| Metallicity [Fe/H] | 0.350 dex |
| Stellar Age | 5.100 Gyr |
| Apparent Magnitude | V: 12.775 · G: 12.677 |
| System Architecture | 1 Star, 5 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.235796 AU |
| Orbital Period | 2047.635 days |
| Mean Orbital Velocity | 17.2 km/s |
| Orbital Eccentricity (e) | 0.01312 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.81 g/cm³ (58.8 km/s vesc) |
| Insolation Flux | 0.0991 S⊕ (~135 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1275.400 LY (391.038 pc) |