Kepler-1122 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1122 b is a confirmed sub-neptune exoplanet orbiting the star Kepler-1122, located approximately 4013.1 light-years (1230.42 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0442% across the stellar disk), this world measures 2.04 Earth radii and has a measured mass of 4.82 Earth masses. Combining its mass and radius yields a mean bulk density of 3.13 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 17.2 km/s.
In its orbital architecture around Kepler-1122, Kepler-1122 b completes one full revolution every 42.192 Earth days at a semi-major axis of 0.2315 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 59.7 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 526 K (+253°C / +487°F) and receiving 23.26 S⊕ (~31,661 W/m²), Kepler-1122 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1122 is classified as a stellar host with an effective photospheric temperature of 5,544 K, a radius of 0.89 R☉, a mass of 0.92 M☉, an estimated bolometric luminosity of 0.671 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.68 Gyr and a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-1122 shines at apparent V-band magnitude 15.405 (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-1122 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,544 K |
| Stellar Radius | 0.8900 R☉ |
| Stellar Mass | 0.9200 M☉ |
| Bolometric Luminosity | 0.671 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | 4.680 Gyr |
| Apparent Magnitude | V: 15.405 · G: 15.103 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.231500 AU |
| Orbital Period | 42.192 days |
| Mean Orbital Velocity | 59.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9200° |
| Mean Bulk Density | 3.13 g/cm³ (17.2 km/s vesc) |
| Insolation Flux | 23.2630 S⊕ (~31,661 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4013.100 LY (1230.420 pc) |