HD 102956 b
Astrophysical Synthesis & Habitability Characterization
HD 102956 b is a confirmed gas giant exoplanet orbiting the star HD 102956, located approximately 397.6 light-years (121.89 parsecs) from the Solar System. First announced in 2010 by W. M. Keck Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.8 Earth radii (1.23 Jupiter radii) and has a measured mass of 305.117 Earth masses (0.96 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.64 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.6 g⊕ (15.69 m/s²), and an escape velocity of 52.6 km/s.
In its orbital architecture around HD 102956, HD 102956 b completes one full revolution every 6.495 Earth days at a semi-major axis of 0.0807 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 135.2 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.037 (ranging from 0.0777 AU at periapsis to 0.0837 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1805 K (+1532°C / +2790°F) and receiving 1,781.19 S⊕ (~2,424,203 W/m²), HD 102956 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 102956 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 4,985 K, a radius of 4.55 R☉, a mass of 1.66 M☉, an estimated bolometric luminosity of 11.47 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.3 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, HD 102956 shines at apparent V-band magnitude 7.86 (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: W. M. Keck Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 102956 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 4,985 K |
| Stellar Radius | 4.5500 R☉ |
| Stellar Mass | 1.6600 M☉ |
| Bolometric Luminosity | 11.47 L☉ |
| Metallicity [Fe/H] | 0.190 dex |
| Stellar Age | 2.300 Gyr |
| Apparent Magnitude | V: 7.860 · G: 7.608 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.080700 AU |
| Orbital Period | 6.495 days |
| Mean Orbital Velocity | 135.2 km/s |
| Orbital Eccentricity (e) | 0.03700 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.64 g/cm³ (52.6 km/s vesc) |
| Insolation Flux | 1781.1928 S⊕ (~2,424,203 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 397.600 LY (121.890 pc) |