Kepler-181 b
Astrophysical Synthesis & Habitability Characterization
Kepler-181 b is a confirmed super-earth exoplanet orbiting the star Kepler-181, located approximately 1987.2 light-years (609.28 parsecs) from the Solar System. First announced in 2014 by Kepler using the Transit detection technique (producing an estimated primary transit depth of 0.0242% across the stellar disk), this world measures 1.27 Earth radii and has a measured mass of 2.15 Earth masses. Combining its mass and radius yields a mean bulk density of 5.79 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.33 g⊕ (13.04 m/s²), and an escape velocity of 14.6 km/s.
In its orbital architecture around Kepler-181, Kepler-181 b completes one full revolution every 3.138 Earth days at a semi-major axis of 0.04 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 138.7 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 1041 K (+768°C / +1414°F) and receiving 255.58 S⊕ (~347,850 W/m²), Kepler-181 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Kepler-181 is classified as a stellar host with an effective photospheric temperature of 5,333 K, a radius of 0.749 R☉, a mass of 0.81 M☉, an estimated bolometric luminosity of 0.407 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.46 Gyr and a metallicity of [Fe/H] = -0.04 dex (near-solar heavy-element abundance). From Earth, Kepler-181 shines at apparent V-band magnitude 14.854 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The Kepler-181 system is a multi-planet architecture hosting 2 confirmed worlds, with Kepler-181 b sharing its stellar neighborhood alongside Kepler-181 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-181 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,333 K |
| Stellar Radius | 0.7490 R☉ |
| Stellar Mass | 0.8100 M☉ |
| Bolometric Luminosity | 0.407 L☉ |
| Metallicity [Fe/H] | -0.040 dex |
| Stellar Age | 6.460 Gyr |
| Apparent Magnitude | V: 14.854 · G: 14.714 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.040000 AU |
| Orbital Period | 3.138 days |
| Mean Orbital Velocity | 138.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.7200° |
| Mean Bulk Density | 5.79 g/cm³ (14.6 km/s vesc) |
| Insolation Flux | 255.5840 S⊕ (~347,850 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1987.200 LY (609.283 pc) |