Kepler-26 e
Astrophysical Synthesis & Habitability Characterization
Kepler-26 e is a confirmed sub-neptune exoplanet orbiting the star Kepler-26, located approximately 1093.6 light-years (335.31 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.1497% across the stellar disk), this world measures 2.41 Earth radii and has a measured mass of 6.39 Earth masses. Combining its mass and radius yields a mean bulk density of 2.52 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.2 km/s.
In its orbital architecture around Kepler-26, Kepler-26 e completes one full revolution every 46.828 Earth days at a semi-major axis of 0.22 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 51.1 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 2.410 R⊕, Kepler-26 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-26 is classified as a low-mass red dwarf of spectral type M0 V with an effective photospheric temperature of 4,486 K, a radius of 0.571 R☉, a mass of 0.593 M☉, an estimated bolometric luminosity of 0.118 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.95 Gyr and a metallicity of [Fe/H] = -0.21 dex (metal-poor relative to the Sun). From Earth, Kepler-26 shines at apparent V-band magnitude 15.853 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-26 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-26 e sharing its stellar neighborhood alongside Kepler-26 d, Kepler-26 b, Kepler-26 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-26 |
| Spectral Type | M0 V |
| Effective Temp (Teff) | 4,486 K |
| Stellar Radius | 0.5710 R☉ |
| Stellar Mass | 0.5930 M☉ |
| Bolometric Luminosity | 0.118 L☉ |
| Metallicity [Fe/H] | -0.210 dex |
| Stellar Age | 2.950 Gyr |
| Apparent Magnitude | V: 15.853 · G: 15.409 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.220000 AU |
| Orbital Period | 46.828 days |
| Mean Orbital Velocity | 51.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.8700° |
| Mean Bulk Density | 2.52 g/cm³ (18.2 km/s vesc) |
| Insolation Flux | 1.7530 S⊕ (~2,386 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1093.600 LY (335.307 pc) |