HD 22496 b
Astrophysical Synthesis & Habitability Characterization
HD 22496 b is a confirmed sub-neptune exoplanet orbiting the star HD 22496, located approximately 44.3 light-years (13.6 parsecs) from the Solar System. First announced in 2021 by Paranal Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.22 Earth radii and has a measured mass of 5.57 Earth masses. Combining its mass and radius yields a mean bulk density of 2.81 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.13 g⊕ (11.08 m/s²), and an escape velocity of 17.7 km/s.
In its orbital architecture around HD 22496, HD 22496 b completes one full revolution every 5.091 Earth days at a semi-major axis of 0.051 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 109 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 573 K (+300°C / +572°F) and receiving 26.00 S⊕ (~35,386 W/m²), HD 22496 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HD 22496 is classified as an orange K-type star of spectral type K5/M0V with an effective photospheric temperature of 4,385 K, a radius of 0.674 R☉, a mass of 0.684 M☉, an estimated bolometric luminosity of 0.151 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.08 dex (near-solar heavy-element abundance). From Earth, HD 22496 shines at apparent V-band magnitude 8.57 (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: Paranal Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 22496 |
| Spectral Type | K5/M0V |
| Effective Temp (Teff) | 4,385 K |
| Stellar Radius | 0.6740 R☉ |
| Stellar Mass | 0.6840 M☉ |
| Bolometric Luminosity | 0.151 L☉ |
| Metallicity [Fe/H] | -0.080 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.570 · G: 8.019 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.051000 AU |
| Orbital Period | 5.091 days |
| Mean Orbital Velocity | 109 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.81 g/cm³ (17.7 km/s vesc) |
| Insolation Flux | 26.0000 S⊕ (~35,386 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 44.300 LY (13.596 pc) |