HD 125271 b
Astrophysical Synthesis & Habitability Characterization
HD 125271 b is a confirmed gas giant exoplanet orbiting the star HD 125271, located approximately 128.3 light-years (39.35 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories 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 3465.601 Earth masses (10.9 Jupiter masses). Combining its mass and radius yields a mean bulk density of 10.02 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 22.54 g⊕ (221.04 m/s²), and an escape velocity of 187 km/s.
In its orbital architecture around HD 125271, HD 125271 b completes one full revolution every 14901.993 Earth days (40.8Julian years) at a semi-major axis of 10.817 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 7.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.165 carries the world between 9.0322 AU at periapsis and 12.6018 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 60 K (-213°C / -351°F) and an incident flux of 0.00 S⊕ (~3 W/m²), surface water and volatile species on HD 125271 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 125271 is classified as a stellar host with an effective photospheric temperature of 4,704 K, a radius of 0.7514 R☉, a mass of 0.75 M☉, an estimated bolometric luminosity of 0.248 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.22 dex (metal-poor relative to the Sun). From Earth, HD 125271 shines at apparent V-band magnitude 9.68 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 125271 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,704 K |
| Stellar Radius | 0.7514 R☉ |
| Stellar Mass | 0.7500 M☉ |
| Bolometric Luminosity | 0.248 L☉ |
| Metallicity [Fe/H] | -0.220 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.680 · G: 9.356 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 10.817000 AU |
| Orbital Period | 14901.993 days |
| Mean Orbital Velocity | 7.9 km/s |
| Orbital Eccentricity (e) | 0.16500 |
| Orbital Inclination (i) | 93.0880° |
| Mean Bulk Density | 10.02 g/cm³ (187 km/s vesc) |
| Insolation Flux | 0.0021 S⊕ (~3 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 128.300 LY (39.347 pc) |