HD 156411 b
Astrophysical Synthesis & Habitability Characterization
HD 156411 b is a confirmed gas giant exoplanet orbiting the star HD 156411, located approximately 185.5 light-years (56.87 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 14 Earth radii (1.25 Jupiter radii) and has a measured mass of 235.18 Earth masses (0.74 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.47 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.2 g⊕ (11.77 m/s²), and an escape velocity of 45.8 km/s.
In its orbital architecture around HD 156411, HD 156411 b completes one full revolution every 842.2 Earth days (2.31Julian years) at a semi-major axis of 1.88 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 24.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.22 carries the world between 1.4664 AU at periapsis and 2.2936 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 14.000 R⊕, HD 156411 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 156411 is classified as a warm F-type star of spectral type F8 IV/V with an effective photospheric temperature of 5,900 K, a radius of 2.16 R☉, a mass of 1.25 M☉, an estimated bolometric luminosity of 5.072 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.28 Gyr and a metallicity of [Fe/H] = -0.12 dex (metal-poor relative to the Sun). From Earth, HD 156411 shines at apparent V-band magnitude 6.67 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 156411 |
| Spectral Type | F8 IV/V |
| Effective Temp (Teff) | 5,900 K |
| Stellar Radius | 2.1600 R☉ |
| Stellar Mass | 1.2500 M☉ |
| Bolometric Luminosity | 5.072 L☉ |
| Metallicity [Fe/H] | -0.120 dex |
| Stellar Age | 4.280 Gyr |
| Apparent Magnitude | V: 6.670 · G: 6.512 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.880000 AU |
| Orbital Period | 842.2 days |
| Mean Orbital Velocity | 24.3 km/s |
| Orbital Eccentricity (e) | 0.22000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.47 g/cm³ (45.8 km/s vesc) |
| Insolation Flux | 1.5229 S⊕ (~2,073 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 185.500 LY (56.866 pc) |