HD 149143 b
Astrophysical Synthesis & Habitability Characterization
HD 149143 b is a confirmed gas giant exoplanet orbiting the star HD 149143, located approximately 239 light-years (73.28 parsecs) from the Solar System. First announced in 2005 by Haute-Provence Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.6 Earth radii (1.21 Jupiter radii) and has a measured mass of 422.714 Earth masses (1.33 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.93 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.29 g⊕ (22.46 m/s²), and an escape velocity of 62.4 km/s.
In its orbital architecture around HD 149143, HD 149143 b completes one full revolution every 4.072 Earth days at a semi-major axis of 0.053 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 141.6 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0167 (ranging from 0.0521 AU at periapsis to 0.0539 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1472 K (+1199°C / +2190°F) and receiving 796.98 S⊕ (~1,084,692 W/m²), HD 149143 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 149143 is classified as a solar-type yellow star of spectral type G0 with an effective photospheric temperature of 5,856 K, a radius of 1.44 R☉, a mass of 1.2 M☉, an estimated bolometric luminosity of 2.188 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.28 Gyr and a metallicity of [Fe/H] = 0.29 dex (metal-rich relative to the Sun). From Earth, HD 149143 shines at apparent V-band magnitude 7.89 (accessible to binoculars and small amateur telescopes) 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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 149143 |
| Spectral Type | G0 |
| Effective Temp (Teff) | 5,856 K |
| Stellar Radius | 1.4400 R☉ |
| Stellar Mass | 1.2000 M☉ |
| Bolometric Luminosity | 2.188 L☉ |
| Metallicity [Fe/H] | 0.290 dex |
| Stellar Age | 4.280 Gyr |
| Apparent Magnitude | V: 7.890 · G: 7.741 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.053000 AU |
| Orbital Period | 4.072 days |
| Mean Orbital Velocity | 141.6 km/s |
| Orbital Eccentricity (e) | 0.01670 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.93 g/cm³ (62.4 km/s vesc) |
| Insolation Flux | 796.9815 S⊕ (~1,084,692 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 239.000 LY (73.280 pc) |