HD 125136 b
Astrophysical Synthesis & Habitability Characterization
HD 125136 b is a confirmed gas giant exoplanet orbiting the star HD 125136, located approximately 395.5 light-years (121.26 parsecs) from the Solar System. First announced in 2026 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.3 Earth radii (1.19 Jupiter radii) and has a measured mass of 718.292 Earth masses (2.26 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.68 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.06 g⊕ (39.81 m/s²), and an escape velocity of 82.2 km/s.
In its orbital architecture around HD 125136, HD 125136 b completes one full revolution every 849.77 Earth days (2.33Julian years). Its moderate orbital eccentricity of e = 0.05 driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.300 R⊕, HD 125136 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 125136 is classified as a stellar host with an effective photospheric temperature of 4,959 K, a radius of 5.39 R☉, a mass of 1.55 M☉, an estimated bolometric luminosity of 15.763 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.03 Gyr and a metallicity of [Fe/H] = 0.02 dex (near-solar heavy-element abundance). From Earth, HD 125136 shines at apparent V-band magnitude 7.44 (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 125136 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,959 K |
| Stellar Radius | 5.3900 R☉ |
| Stellar Mass | 1.5500 M☉ |
| Bolometric Luminosity | 15.763 L☉ |
| Metallicity [Fe/H] | 0.020 dex |
| Stellar Age | 4.030 Gyr |
| Apparent Magnitude | V: 7.440 · G: 7.172 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 849.77 days |
| Orbital Eccentricity (e) | 0.05000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.68 g/cm³ (82.2 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 395.500 LY (121.257 pc) |