HD 125612 d
Astrophysical Synthesis & Habitability Characterization
HD 125612 d is a confirmed gas giant exoplanet orbiting the star HD 125612, located approximately 187.9 light-years (57.62 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 12.7 Earth radii (1.13 Jupiter radii) and has a measured mass of 2281.372 Earth masses (7.18 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6.14 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 14.14 g⊕ (138.67 m/s²), and an escape velocity of 149.9 km/s.
In its orbital architecture around HD 125612, HD 125612 d completes one full revolution every 2822.727 Earth days (7.73Julian years) at a semi-major axis of 3.982 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 15.3 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.115 carries the world between 3.5241 AU at periapsis and 4.4399 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 147 K (-126°C / -195°F) and an incident flux of 0.07 S⊕ (~99 W/m²), surface water and volatile species on HD 125612 d would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 125612 is classified as a solar-type yellow star of spectral type G3 V with an effective photospheric temperature of 5,900 K, a radius of 1.07 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 1.245 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.77 Gyr and a metallicity of [Fe/H] = 0.23 dex (metal-rich relative to the Sun). From Earth, HD 125612 shines at apparent V-band magnitude 8.31 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The HD 125612 system is a multi-planet architecture hosting 3 confirmed worlds, with HD 125612 d sharing its stellar neighborhood alongside HD 125612 c, HD 125612 b.
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 125612 |
| Spectral Type | G3 V |
| Effective Temp (Teff) | 5,900 K |
| Stellar Radius | 1.0700 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 1.245 L☉ |
| Metallicity [Fe/H] | 0.230 dex |
| Stellar Age | 1.770 Gyr |
| Apparent Magnitude | V: 8.310 · G: 8.156 |
| System Architecture | 2 Stars, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 3.982000 AU |
| Orbital Period | 2822.727 days |
| Mean Orbital Velocity | 15.3 km/s |
| Orbital Eccentricity (e) | 0.11500 |
| Orbital Inclination (i) | 88.1950° |
| Mean Bulk Density | 6.14 g/cm³ (149.9 km/s vesc) |
| Insolation Flux | 0.0724 S⊕ (~99 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 187.900 LY (57.621 pc) |