Kepler-128 b
Astrophysical Synthesis & Habitability Characterization
Kepler-128 b is a confirmed super-earth exoplanet orbiting the star Kepler-128, located approximately 1292.8 light-years (396.38 parsecs) from the Solar System. First announced in 2013 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0062% across the stellar disk), this world measures 1.421 Earth radii and has a measured mass of 3.79 Earth masses. Combining its mass and radius yields a mean bulk density of 7.28 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 1.88 g⊕ (18.44 m/s²), and an escape velocity of 18.3 km/s.
In its orbital architecture around Kepler-128, Kepler-128 b completes one full revolution every 15 Earth days at a semi-major axis of 0.12545 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 91 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 968 K (+695°C / +1283°F) and receiving 227.40 S⊕ (~309,489 W/m²), Kepler-128 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-128 is classified as a stellar host with an effective photospheric temperature of 6,072 K, a radius of 1.659 R☉, a mass of 1.184 M☉, an estimated bolometric luminosity of 3.357 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.07 Gyr and a metallicity of [Fe/H] = -0.03 dex (near-solar heavy-element abundance). From Earth, Kepler-128 shines at apparent V-band magnitude 11.693 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-128 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-128 b sharing its stellar neighborhood alongside Kepler-128 c.
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-128 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,072 K |
| Stellar Radius | 1.6590 R☉ |
| Stellar Mass | 1.1840 M☉ |
| Bolometric Luminosity | 3.357 L☉ |
| Metallicity [Fe/H] | -0.030 dex |
| Stellar Age | 4.070 Gyr |
| Apparent Magnitude | V: 11.693 · G: 11.289 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.125450 AU |
| Orbital Period | 15 days |
| Mean Orbital Velocity | 91 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.9600° |
| Mean Bulk Density | 7.28 g/cm³ (18.3 km/s vesc) |
| Insolation Flux | 227.3980 S⊕ (~309,489 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1292.800 LY (396.379 pc) |