HD 143361 b
Astrophysical Synthesis & Habitability Characterization
HD 143361 b is a confirmed gas giant exoplanet orbiting the star HD 143361, located approximately 223.5 light-years (68.52 parsecs) from the Solar System. First announced in 2008 by Las Campanas Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.9 Earth radii (1.15 Jupiter radii) and has a measured mass of 1382.554 Earth masses (4.35 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.55 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 8.31 g⊕ (81.49 m/s²), and an escape velocity of 115.8 km/s.
In its orbital architecture around HD 143361, HD 143361 b completes one full revolution every 1039.15 Earth days (2.85Julian years) at a semi-major axis of 1.988 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 20.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.197 carries the world between 1.5964 AU at periapsis and 2.3796 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.900 R⊕, HD 143361 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 143361 is classified as a solar-type yellow star of spectral type G6 V with an effective photospheric temperature of 5,507 K, a radius of 0.916 R☉, a mass of 0.968 M☉, an estimated bolometric luminosity of 0.692 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.942 Gyr and a metallicity of [Fe/H] = 0.14 dex (metal-rich relative to the Sun). From Earth, HD 143361 shines at apparent V-band magnitude 9.2 (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: Las Campanas Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 143361 |
| Spectral Type | G6 V |
| Effective Temp (Teff) | 5,507 K |
| Stellar Radius | 0.9160 R☉ |
| Stellar Mass | 0.9680 M☉ |
| Bolometric Luminosity | 0.692 L☉ |
| Metallicity [Fe/H] | 0.140 dex |
| Stellar Age | 2.942 Gyr |
| Apparent Magnitude | V: 9.200 · G: 9.016 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.988000 AU |
| Orbital Period | 1039.15 days |
| Mean Orbital Velocity | 20.8 km/s |
| Orbital Eccentricity (e) | 0.19700 |
| Orbital Inclination (i) | 50.0000° |
| Mean Bulk Density | 3.55 g/cm³ (115.8 km/s vesc) |
| Insolation Flux | 0.2050 S⊕ (~279 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 223.500 LY (68.515 pc) |