Kepler-68 e
Astrophysical Synthesis & Habitability Characterization
Kepler-68 e is a confirmed gas giant exoplanet orbiting the star Kepler-68, located approximately 470.2 light-years (144.17 parsecs) from the Solar System. First announced in 2023 by Roque de los Muchachos Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 11.2 Earth radii (1 Jupiter radii) and has a measured mass of 86.449 Earth masses (0.27 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.34 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.69 g⊕ (6.77 m/s²), and an escape velocity of 31.1 km/s.
In its orbital architecture around Kepler-68, Kepler-68 e completes one full revolution every 3455 Earth days (9.46Julian years) at a semi-major axis of 4.6 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 14.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.33, swinging from 3.082 AU at periapsis out to 6.118 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 147 K (-126°C / -195°F) and an incident flux of 0.08 S⊕ (~110 W/m²), surface water and volatile species on Kepler-68 e would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star Kepler-68 is classified as a stellar host with an effective photospheric temperature of 5,847 K, a radius of 1.2564 R☉, a mass of 1.057 M☉, an estimated bolometric luminosity of 1.655 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.84 Gyr and a metallicity of [Fe/H] = 0.11 dex (metal-rich relative to the Sun). From Earth, Kepler-68 shines at apparent V-band magnitude 10.077 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-68 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-68 e sharing its stellar neighborhood alongside Kepler-68 b, Kepler-68 c, Kepler-68 d.
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: Roque de los Muchachos Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Kepler-68 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,847 K |
| Stellar Radius | 1.2564 R☉ |
| Stellar Mass | 1.0570 M☉ |
| Bolometric Luminosity | 1.655 L☉ |
| Metallicity [Fe/H] | 0.110 dex |
| Stellar Age | 6.840 Gyr |
| Apparent Magnitude | V: 10.077 · G: 9.934 |
| System Architecture | 2 Stars, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 4.600000 AU |
| Orbital Period | 3455 days |
| Mean Orbital Velocity | 14.5 km/s |
| Orbital Eccentricity (e) | 0.33000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.34 g/cm³ (31.1 km/s vesc) |
| Insolation Flux | 0.0805 S⊕ (~110 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 470.200 LY (144.166 pc) |