Kepler-722 c
Astrophysical Synthesis & Habitability Characterization
Kepler-722 c is a confirmed sub-neptune exoplanet orbiting the star Kepler-722, located approximately 4042.7 light-years (1239.5 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0606% across the stellar disk), this world measures 2.82 Earth radii and has a measured mass of 8.35 Earth masses. Combining its mass and radius yields a mean bulk density of 2.05 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.05 g⊕ (10.3 m/s²), and an escape velocity of 19.2 km/s.
In its orbital architecture around Kepler-722, Kepler-722 c completes one full revolution every 105.145 Earth days at a semi-major axis of 0.4471 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 46.3 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 401 K (+128°C / +262°F) and receiving 5.48 S⊕ (~7,458 W/m²), Kepler-722 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-722 is classified as a stellar host with an effective photospheric temperature of 5,863 K, a radius of 1.05 R☉, a mass of 1.03 M☉, an estimated bolometric luminosity of 1.169 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.37 Gyr and a metallicity of [Fe/H] = 0.02 dex (near-solar heavy-element abundance). From Earth, Kepler-722 shines at apparent V-band magnitude 15.489 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-722 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-722 c sharing its stellar neighborhood alongside Kepler-722 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-722 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,863 K |
| Stellar Radius | 1.0500 R☉ |
| Stellar Mass | 1.0300 M☉ |
| Bolometric Luminosity | 1.169 L☉ |
| Metallicity [Fe/H] | 0.020 dex |
| Stellar Age | 4.370 Gyr |
| Apparent Magnitude | V: 15.489 · G: 15.373 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.447100 AU |
| Orbital Period | 105.145 days |
| Mean Orbital Velocity | 46.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.3900° |
| Mean Bulk Density | 2.05 g/cm³ (19.2 km/s vesc) |
| Insolation Flux | 5.4800 S⊕ (~7,458 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4042.700 LY (1239.500 pc) |