Kepler-279 d
Astrophysical Synthesis & Habitability Characterization
Kepler-279 d is a confirmed sub-neptune exoplanet orbiting the star Kepler-279, located approximately 3383.5 light-years (1037.4 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0706% across the stellar disk), this world measures 3.1 Earth radii (0.28 Jupiter radii) and has a measured mass of 37.5 Earth masses (0.12 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6.94 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3.9 g⊕ (38.25 m/s²), and an escape velocity of 38.9 km/s.
In its orbital architecture around Kepler-279, Kepler-279 d completes one full revolution every 54.414 Earth days at a semi-major axis of 0.2901 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 58 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.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 574 K (+301°C / +574°F) and receiving 35.74 S⊕ (~48,641 W/m²), Kepler-279 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-279 is classified as a stellar host with an effective photospheric temperature of 6,689 K, a radius of 1.07 R☉, a mass of 1.1 M☉, an estimated bolometric luminosity of 2.056 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.22 Gyr and a metallicity of [Fe/H] = -0.114 dex (metal-poor relative to the Sun). From Earth, Kepler-279 shines at apparent V-band magnitude 13.647 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-279 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-279 d sharing its stellar neighborhood alongside Kepler-279 b, Kepler-279 c, Kepler-279 e.
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-279 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,689 K |
| Stellar Radius | 1.0700 R☉ |
| Stellar Mass | 1.1000 M☉ |
| Bolometric Luminosity | 2.056 L☉ |
| Metallicity [Fe/H] | -0.114 dex |
| Stellar Age | 0.220 Gyr |
| Apparent Magnitude | V: 13.647 · G: 13.585 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.290100 AU |
| Orbital Period | 54.414 days |
| Mean Orbital Velocity | 58 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.0900° |
| Mean Bulk Density | 6.94 g/cm³ (38.9 km/s vesc) |
| Insolation Flux | 35.7390 S⊕ (~48,641 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3383.500 LY (1037.400 pc) |