Kepler-299 d
Astrophysical Synthesis & Habitability Characterization
Kepler-299 d is a confirmed super-earth exoplanet orbiting the star Kepler-299, located approximately 3431.9 light-years (1052.24 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0273% across the stellar disk), this world measures 1.86 Earth radii and has a measured mass of 4.12 Earth masses. Combining its mass and radius yields a mean bulk density of 3.53 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.19 g⊕ (11.67 m/s²), and an escape velocity of 16.6 km/s.
In its orbital architecture around Kepler-299, Kepler-299 d completes one full revolution every 15.055 Earth days at a semi-major axis of 0.118 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 85.3 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 729 K (+456°C / +853°F) and receiving 69.96 S⊕ (~95,216 W/m²), Kepler-299 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-299 is classified as a stellar host with an effective photospheric temperature of 5,617 K, a radius of 1.032 R☉, a mass of 1.004 M☉, an estimated bolometric luminosity of 0.951 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.24 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, Kepler-299 shines at apparent V-band magnitude 15.232 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-299 system is a multi-planet architecture hosting 4 confirmed worlds, with Kepler-299 d sharing its stellar neighborhood alongside Kepler-299 b, Kepler-299 c, Kepler-299 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-299 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,617 K |
| Stellar Radius | 1.0320 R☉ |
| Stellar Mass | 1.0040 M☉ |
| Bolometric Luminosity | 0.951 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 3.240 Gyr |
| Apparent Magnitude | V: 15.232 · G: 15.010 |
| System Architecture | 1 Star, 4 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.118000 AU |
| Orbital Period | 15.055 days |
| Mean Orbital Velocity | 85.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.2000° |
| Mean Bulk Density | 3.53 g/cm³ (16.6 km/s vesc) |
| Insolation Flux | 69.9600 S⊕ (~95,216 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3431.900 LY (1052.240 pc) |