HD 127506 b
Astrophysical Synthesis & Habitability Characterization
HD 127506 b is a confirmed sub-neptune exoplanet orbiting the star HD 127506, located approximately 73.5 light-years (22.53 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 5.67 Earth radii (0.51 Jupiter radii) and has a measured mass of 27.333 Earth masses. Combining its mass and radius yields a mean bulk density of 0.83 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.85 g⊕ (8.34 m/s²), and an escape velocity of 24.6 km/s.
In its orbital architecture around HD 127506, HD 127506 b completes one full revolution every 65.784 Earth days at a semi-major axis of 0.287 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 47.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.24 carries the world between 0.2181 AU at periapsis and 0.3559 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 355 K (+82°C / +180°F) and receiving 2.64 S⊕ (~3,594 W/m²), HD 127506 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 127506 is classified as an orange K-type star of spectral type K3V with an effective photospheric temperature of 4,595 K, a radius of 0.7358 R☉, a mass of 0.73 M☉, an estimated bolometric luminosity of 0.217 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.08 dex (near-solar heavy-element abundance). From Earth, HD 127506 shines at apparent V-band magnitude 8.7 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 127506 |
| Spectral Type | K3V |
| Effective Temp (Teff) | 4,595 K |
| Stellar Radius | 0.7358 R☉ |
| Stellar Mass | 0.7300 M☉ |
| Bolometric Luminosity | 0.217 L☉ |
| Metallicity [Fe/H] | -0.080 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.700 · G: 8.332 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.287000 AU |
| Orbital Period | 65.784 days |
| Mean Orbital Velocity | 47.5 km/s |
| Orbital Eccentricity (e) | 0.24000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.83 g/cm³ (24.6 km/s vesc) |
| Insolation Flux | 2.6404 S⊕ (~3,594 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 73.500 LY (22.528 pc) |