Kepler-291 c
Astrophysical Synthesis & Habitability Characterization
Kepler-291 c is a confirmed super-earth exoplanet orbiting the star Kepler-291, located approximately 5826.7 light-years (1786.48 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0288% across the stellar disk), this world measures 1.88 Earth radii and has a measured mass of 4.19 Earth masses. Combining its mass and radius yields a mean bulk density of 3.48 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 16.7 km/s.
In its orbital architecture around Kepler-291, Kepler-291 c completes one full revolution every 5.701 Earth days at a semi-major axis of 0.065 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 124 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 1035 K (+762°C / +1404°F) and receiving 332.74 S⊕ (~452,855 W/m²), Kepler-291 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-291 is classified as a stellar host with an effective photospheric temperature of 6,002 K, a radius of 1.016 R☉, a mass of 1.023 M☉, an estimated bolometric luminosity of 1.202 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.76 Gyr and a metallicity of [Fe/H] = 0.23 dex (metal-rich relative to the Sun). From Earth, Kepler-291 shines at apparent V-band magnitude 16.218 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-291 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-291 c sharing its stellar neighborhood alongside Kepler-291 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-291 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,002 K |
| Stellar Radius | 1.0160 R☉ |
| Stellar Mass | 1.0230 M☉ |
| Bolometric Luminosity | 1.202 L☉ |
| Metallicity [Fe/H] | 0.230 dex |
| Stellar Age | 7.760 Gyr |
| Apparent Magnitude | V: 16.218 · G: 15.899 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.065000 AU |
| Orbital Period | 5.701 days |
| Mean Orbital Velocity | 124 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.1500° |
| Mean Bulk Density | 3.48 g/cm³ (16.7 km/s vesc) |
| Insolation Flux | 332.7370 S⊕ (~452,855 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 5826.700 LY (1786.480 pc) |