HATS-22 b
Astrophysical Synthesis & Habitability Characterization
HATS-22 b is a confirmed gas giant exoplanet orbiting the star HATS-22, located approximately 748.6 light-years (229.52 parsecs) from the Solar System. First announced in 2017 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 2.0203% across the stellar disk), this world measures 10.682 Earth radii (0.95 Jupiter radii) and has a measured mass of 870.854 Earth masses (2.74 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.94 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 7.63 g⊕ (74.82 m/s²), and an escape velocity of 101 km/s.
In its orbital architecture around HATS-22, HATS-22 b completes one full revolution every 4.723 Earth days at a semi-major axis of 0.05025 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 115.8 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.079 carries the world between 0.0463 AU at periapsis and 0.0542 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 858 K (+585°C / +1085°F) and receiving 111.30 S⊕ (~151,478 W/m²), HATS-22 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-22 is classified as an orange K-type star of spectral type K V with an effective photospheric temperature of 4,803 K, a radius of 0.689 R☉, a mass of 0.759 M☉, an estimated bolometric luminosity of 0.227 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, HATS-22 shines at apparent V-band magnitude 13.397 (faint and requiring research-grade or CCD telescopic photometry) 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: HATSouth · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HATS-22 |
| Spectral Type | K V |
| Effective Temp (Teff) | 4,803 K |
| Stellar Radius | 0.6890 R☉ |
| Stellar Mass | 0.7590 M☉ |
| Bolometric Luminosity | 0.227 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.397 · G: 13.123 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.050250 AU |
| Orbital Period | 4.723 days |
| Mean Orbital Velocity | 115.8 km/s |
| Orbital Eccentricity (e) | 0.07900 |
| Orbital Inclination (i) | 87.9600° |
| Mean Bulk Density | 3.94 g/cm³ (101 km/s vesc) |
| Insolation Flux | 111.2990 S⊕ (~151,478 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 748.600 LY (229.518 pc) |