HD 156846 b
Astrophysical Synthesis & Habitability Characterization
HD 156846 b is a confirmed gas giant exoplanet orbiting the star HD 156846, located approximately 155.7 light-years (47.73 parsecs) from the Solar System. First announced in 2007 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.4 Earth radii (1.11 Jupiter radii) and has a measured mass of 3391.246 Earth masses (10.67 Jupiter masses). Combining its mass and radius yields a mean bulk density of 9.81 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 22.06 g⊕ (216.33 m/s²), and an escape velocity of 185 km/s.
In its orbital architecture around HD 156846, HD 156846 b completes one full revolution every 359.51 Earth days at a semi-major axis of 1.12 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 33.9 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.85, swinging from 0.168 AU at periapsis out to 2.072 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 382 K (+109°C / +228°F) and receiving 3.97 S⊕ (~5,403 W/m²), HD 156846 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 156846 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 6,090 K, a radius of 1.9 R☉, a mass of 1.38 M☉, an estimated bolometric luminosity of 4.455 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.4 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, HD 156846 shines at apparent V-band magnitude 6.5 (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 156846 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 6,090 K |
| Stellar Radius | 1.9000 R☉ |
| Stellar Mass | 1.3800 M☉ |
| Bolometric Luminosity | 4.455 L☉ |
| Metallicity [Fe/H] | 0.150 dex |
| Stellar Age | 2.400 Gyr |
| Apparent Magnitude | V: 6.500 · G: 6.362 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.120000 AU |
| Orbital Period | 359.51 days |
| Mean Orbital Velocity | 33.9 km/s |
| Orbital Eccentricity (e) | 0.85000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 9.81 g/cm³ (185 km/s vesc) |
| Insolation Flux | 3.9700 S⊕ (~5,403 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 155.700 LY (47.733 pc) |