Kepler-1299 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1299 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1299, located approximately 4582.3 light-years (1404.94 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0901% across the stellar disk), this world measures 2.98 Earth radii and has a measured mass of 9.17 Earth masses. Combining its mass and radius yields a mean bulk density of 1.91 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.03 g⊕ (10.1 m/s²), and an escape velocity of 19.6 km/s.
In its orbital architecture around Kepler-1299, Kepler-1299 b completes one full revolution every 19.94 Earth days at a semi-major axis of 0.1357 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 74 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 588 K (+315°C / +599°F) and receiving 45.15 S⊕ (~61,444 W/m²), Kepler-1299 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1299 is classified as a stellar host with an effective photospheric temperature of 5,609 K, a radius of 0.91 R☉, a mass of 0.94 M☉, an estimated bolometric luminosity of 0.735 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.37 Gyr and a metallicity of [Fe/H] = -0.01 dex (near-solar heavy-element abundance). From Earth, Kepler-1299 shines at apparent V-band magnitude 15.962 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere.
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-1299 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,609 K |
| Stellar Radius | 0.9100 R☉ |
| Stellar Mass | 0.9400 M☉ |
| Bolometric Luminosity | 0.735 L☉ |
| Metallicity [Fe/H] | -0.010 dex |
| Stellar Age | 4.370 Gyr |
| Apparent Magnitude | V: 15.962 · G: 15.900 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.135700 AU |
| Orbital Period | 19.94 days |
| Mean Orbital Velocity | 74 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.5300° |
| Mean Bulk Density | 1.91 g/cm³ (19.6 km/s vesc) |
| Insolation Flux | 45.1460 S⊕ (~61,444 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4582.300 LY (1404.940 pc) |