HD 135872 b
Astrophysical Synthesis & Habitability Characterization
HD 135872 b is a confirmed gas giant exoplanet orbiting the star HD 135872, located approximately 268.8 light-years (82.43 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 12.8 Earth radii (1.14 Jupiter radii) and has a measured mass of 1744.56 Earth masses (5.49 Jupiter masses). Combining its mass and radius yields a mean bulk density of 4.59 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 10.65 g⊕ (104.44 m/s²), and an escape velocity of 130.6 km/s.
In its orbital architecture around HD 135872, HD 135872 b completes one full revolution every 2422.326 Earth days (6.63Julian years) at a semi-major axis of 4.172 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 18.7 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.164 carries the world between 3.4878 AU at periapsis and 4.8562 AU at apoapsis, driving measurable seasonal insolation cycles.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.800 R⊕, HD 135872 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 135872 is classified as a stellar host with an effective photospheric temperature of 4,992 K, a radius of 3.9304 R☉, a mass of 1.646 M☉, an estimated bolometric luminosity of 8.607 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, HD 135872 shines at apparent V-band magnitude 7.281 (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 135872 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,992 K |
| Stellar Radius | 3.9304 R☉ |
| Stellar Mass | 1.6460 M☉ |
| Bolometric Luminosity | 8.607 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 7.281 · G: 7.028 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 4.172000 AU |
| Orbital Period | 2422.326 days |
| Mean Orbital Velocity | 18.7 km/s |
| Orbital Eccentricity (e) | 0.16400 |
| Orbital Inclination (i) | 93.8720° |
| Mean Bulk Density | 4.59 g/cm³ (130.6 km/s vesc) |
| Insolation Flux | 0.4969 S⊕ (~676 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 268.800 LY (82.425 pc) |