Kepler-29 c
Astrophysical Synthesis & Habitability Characterization
Kepler-29 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-29, located approximately 2715.4 light-years (832.53 parsecs) from the Solar System. First announced in 2011 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0859% across the stellar disk), this world measures 2.34 Earth radii and has a measured mass of 4.5 Earth masses. Combining its mass and radius yields a mean bulk density of 1.94 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.82 g⊕ (8.04 m/s²), and an escape velocity of 15.5 km/s.
In its orbital architecture around Kepler-29, Kepler-29 c completes one full revolution every 13.286 Earth days at a semi-major axis of 0.10027 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 82.1 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.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 715 K (+442°C / +828°F) and receiving 34.40 S⊕ (~46,818 W/m²), Kepler-29 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-29 is classified as a stellar host with an effective photospheric temperature of 5,378 K, a radius of 0.732 R☉, a mass of 0.761 M☉, an estimated bolometric luminosity of 0.402 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.3 Gyr and a metallicity of [Fe/H] = -0.44 dex (metal-poor relative to the Sun). From Earth, Kepler-29 shines at apparent V-band magnitude 15.547 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-29 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-29 c sharing its stellar neighborhood alongside Kepler-29 b.
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-29 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,378 K |
| Stellar Radius | 0.7320 R☉ |
| Stellar Mass | 0.7610 M☉ |
| Bolometric Luminosity | 0.402 L☉ |
| Metallicity [Fe/H] | -0.440 dex |
| Stellar Age | 0.300 Gyr |
| Apparent Magnitude | V: 15.547 · G: 15.282 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.100270 AU |
| Orbital Period | 13.286 days |
| Mean Orbital Velocity | 82.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9700° |
| Mean Bulk Density | 1.94 g/cm³ (15.5 km/s vesc) |
| Insolation Flux | 34.4000 S⊕ (~46,818 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2715.400 LY (832.532 pc) |