HD 148427 b
Astrophysical Synthesis & Habitability Characterization
HD 148427 b is a confirmed gas giant exoplanet orbiting the star HD 148427, located approximately 232.7 light-years (71.35 parsecs) from the Solar System. First announced in 2009 by Lick Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.7 Earth radii (1.22 Jupiter radii) and has a measured mass of 381.394 Earth masses (1.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.82 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.03 g⊕ (19.91 m/s²), and an escape velocity of 59 km/s.
In its orbital architecture around HD 148427, HD 148427 b completes one full revolution every 331.9 Earth days at a semi-major axis of 1.11 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 36.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.12 carries the world between 0.9768 AU at periapsis and 1.2432 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 452 K (+179°C / +354°F) and receiving 4.89 S⊕ (~6,656 W/m²), HD 148427 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 148427 is classified as an orange K-type star of spectral type K0 III- IV with an effective photospheric temperature of 5,025 K, a radius of 3.86 R☉, a mass of 1.64 M☉, an estimated bolometric luminosity of 8.523 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.5 Gyr and a metallicity of [Fe/H] = 0.154 dex (metal-rich relative to the Sun). From Earth, HD 148427 shines at apparent V-band magnitude 6.905 (accessible to binoculars and small amateur telescopes) in the Southern 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: Lick Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 148427 |
| Spectral Type | K0 III- IV |
| Effective Temp (Teff) | 5,025 K |
| Stellar Radius | 3.8600 R☉ |
| Stellar Mass | 1.6400 M☉ |
| Bolometric Luminosity | 8.523 L☉ |
| Metallicity [Fe/H] | 0.154 dex |
| Stellar Age | 2.500 Gyr |
| Apparent Magnitude | V: 6.905 · G: 6.635 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.110000 AU |
| Orbital Period | 331.9 days |
| Mean Orbital Velocity | 36.4 km/s |
| Orbital Eccentricity (e) | 0.12000 |
| Orbital Inclination (i) | 90.2000° |
| Mean Bulk Density | 0.82 g/cm³ (59 km/s vesc) |
| Insolation Flux | 4.8905 S⊕ (~6,656 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 232.700 LY (71.350 pc) |