11 UMi b
Astrophysical Synthesis & Habitability Characterization
11 UMi b is a confirmed gas giant exoplanet orbiting the star 11 UMi, located approximately 408.7 light-years (125.32 parsecs) from the Solar System. First announced in 2009 by Thueringer Landessternwarte Tautenburg using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.3 Earth radii (1.1 Jupiter radii) and has a measured mass of 4684.814 Earth masses (14.74 Jupiter masses). Combining its mass and radius yields a mean bulk density of 13.88 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 30.97 g⊕ (303.71 m/s²), and an escape velocity of 218.3 km/s.
In its orbital architecture around 11 UMi, 11 UMi b completes one full revolution every 516.22 Earth days (1.41Julian years) at a semi-major axis of 1.53 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 32.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.08 carries the world between 1.4076 AU at periapsis and 1.6524 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 896 K (+623°C / +1153°F) and receiving 114.85 S⊕ (~156,311 W/m²), 11 UMi b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star 11 UMi is classified as an orange K-type star of spectral type K4 III with an effective photospheric temperature of 4,213 K, a radius of 29.79 R☉, a mass of 2.78 M☉, an estimated bolometric luminosity of 250.84 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.56 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, 11 UMi shines at apparent V-band magnitude 5.013 (visible to the unaided human eye under dark skies) 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: Thueringer Landessternwarte Tautenburg · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | 11 UMi |
| Spectral Type | K4 III |
| Effective Temp (Teff) | 4,213 K |
| Stellar Radius | 29.7900 R☉ |
| Stellar Mass | 2.7800 M☉ |
| Bolometric Luminosity | 250.84 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 1.560 Gyr |
| Apparent Magnitude | V: 5.013 · G: 4.562 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.530000 AU |
| Orbital Period | 516.22 days |
| Mean Orbital Velocity | 32.2 km/s |
| Orbital Eccentricity (e) | 0.08000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 13.88 g/cm³ (218.3 km/s vesc) |
| Insolation Flux | 114.8502 S⊕ (~156,311 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 408.700 LY (125.321 pc) |