HD 207496 b
Astrophysical Synthesis & Habitability Characterization
HD 207496 b is a confirmed sub-neptune exoplanet orbiting the star HD 207496, located approximately 77 light-years (23.61 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.072% across the stellar disk), this world measures 2.25 Earth radii and has a measured mass of 6.1 Earth masses. Combining its mass and radius yields a mean bulk density of 2.95 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.2 g⊕ (11.77 m/s²), and an escape velocity of 18.4 km/s.
In its orbital architecture around HD 207496, HD 207496 b completes one full revolution every 6.441 Earth days at a semi-major axis of 0.0629 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 106.2 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.231 carries the world between 0.0484 AU at periapsis and 0.0774 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 743 K (+470°C / +878°F) and receiving 72.90 S⊕ (~99,217 W/m²), HD 207496 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 207496 is classified as an orange K-type star of spectral type K2.5 V with an effective photospheric temperature of 4,819 K, a radius of 0.769 R☉, a mass of 0.8 M☉, an estimated bolometric luminosity of 0.286 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.52 Gyr and a metallicity of [Fe/H] = 0.095 dex (metal-rich relative to the Sun). From Earth, HD 207496 shines at apparent V-band magnitude 8.23 (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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 207496 |
| Spectral Type | K2.5 V |
| Effective Temp (Teff) | 4,819 K |
| Stellar Radius | 0.7690 R☉ |
| Stellar Mass | 0.8000 M☉ |
| Bolometric Luminosity | 0.286 L☉ |
| Metallicity [Fe/H] | 0.095 dex |
| Stellar Age | 0.520 Gyr |
| Apparent Magnitude | V: 8.230 · G: 7.973 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.062900 AU |
| Orbital Period | 6.441 days |
| Mean Orbital Velocity | 106.2 km/s |
| Orbital Eccentricity (e) | 0.23100 |
| Orbital Inclination (i) | 88.7900° |
| Mean Bulk Density | 2.95 g/cm³ (18.4 km/s vesc) |
| Insolation Flux | 72.9000 S⊕ (~99,217 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 77.000 LY (23.606 pc) |