HD 147018 b
Astrophysical Synthesis & Habitability Characterization
HD 147018 b is a confirmed gas giant exoplanet orbiting the star HD 147018, located approximately 131.9 light-years (40.43 parsecs) from the Solar System. First announced in 2009 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.4 Earth radii (1.2 Jupiter radii) and has a measured mass of 674 Earth masses (2.12 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.54 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.75 g⊕ (36.77 m/s²), and an escape velocity of 79.3 km/s.
In its orbital architecture around HD 147018, HD 147018 b completes one full revolution every 44.236 Earth days at a semi-major axis of 0.2388 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 58.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.4686, swinging from 0.1269 AU at periapsis out to 0.3507 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 520 K (+247°C / +477°F) and receiving 12.48 S⊕ (~16,991 W/m²), HD 147018 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 147018 is classified as a solar-type yellow star of spectral type G9 V with an effective photospheric temperature of 5,441 K, a radius of 0.9379 R☉, a mass of 0.927 M☉, an estimated bolometric luminosity of 0.692 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.36 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, HD 147018 shines at apparent V-band magnitude 8.3 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 147018 system is a multi-planet architecture hosting 2 confirmed worlds, with HD 147018 b sharing its stellar neighborhood alongside HD 147018 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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 147018 |
| Spectral Type | G9 V |
| Effective Temp (Teff) | 5,441 K |
| Stellar Radius | 0.9379 R☉ |
| Stellar Mass | 0.9270 M☉ |
| Bolometric Luminosity | 0.692 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | 6.360 Gyr |
| Apparent Magnitude | V: 8.300 · G: 8.111 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.238800 AU |
| Orbital Period | 44.236 days |
| Mean Orbital Velocity | 58.7 km/s |
| Orbital Eccentricity (e) | 0.46860 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.54 g/cm³ (79.3 km/s vesc) |
| Insolation Flux | 12.4842 S⊕ (~16,991 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 131.900 LY (40.426 pc) |