Kepler-1228 b
Astrophysical Synthesis & Habitability Characterization
Kepler-1228 b is a confirmed super-earth exoplanet orbiting the star Kepler-1228, located approximately 1681.2 light-years (515.45 parsecs) from the Solar System. First announced in 2016 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0364% across the stellar disk), this world measures 1.54 Earth radii and has a measured mass of 2.99 Earth masses. Combining its mass and radius yields a mean bulk density of 4.51 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.26 g⊕ (12.36 m/s²), and an escape velocity of 15.6 km/s.
In its orbital architecture around Kepler-1228, Kepler-1228 b completes one full revolution every 0.577 Earth days at a semi-major axis of 0.01186 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 223.5 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 1757 K (+1484°C / +2703°F) and receiving 1,598.66 S⊕ (~2,175,782 W/m²), Kepler-1228 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-1228 is classified as a stellar host with an effective photospheric temperature of 5,063 K, a radius of 0.74 R☉, a mass of 0.78 M☉, an estimated bolometric luminosity of 0.323 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.13 Gyr and a metallicity of [Fe/H] = -0.18 dex (metal-poor relative to the Sun). From Earth, Kepler-1228 shines at apparent V-band magnitude 15.061 (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-1228 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,063 K |
| Stellar Radius | 0.7400 R☉ |
| Stellar Mass | 0.7800 M☉ |
| Bolometric Luminosity | 0.323 L☉ |
| Metallicity [Fe/H] | -0.180 dex |
| Stellar Age | 5.130 Gyr |
| Apparent Magnitude | V: 15.061 · G: 14.861 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.011860 AU |
| Orbital Period | 0.577 days |
| Mean Orbital Velocity | 223.5 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5600° |
| Mean Bulk Density | 4.51 g/cm³ (15.6 km/s vesc) |
| Insolation Flux | 1598.6640 S⊕ (~2,175,782 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1681.200 LY (515.453 pc) |