HATS-7 b
Astrophysical Synthesis & Habitability Characterization
HATS-7 b is a confirmed gas giant exoplanet orbiting the star HATS-7, located approximately 785.1 light-years (240.71 parsecs) from the Solar System. First announced in 2015 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.504% across the stellar disk), this world measures 6.311 Earth radii (0.56 Jupiter radii) and has a measured mass of 38.14 Earth masses (0.12 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.84 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.96 g⊕ (9.41 m/s²), and an escape velocity of 27.5 km/s.
In its orbital architecture around HATS-7, HATS-7 b completes one full revolution every 3.185 Earth days at a semi-major axis of 0.04012 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 137 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.17 carries the world between 0.0333 AU at periapsis and 0.0469 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1084 K (+811°C / +1492°F) and receiving 211.62 S⊕ (~288,012 W/m²), HATS-7 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-7 is classified as an orange K-type star of spectral type K2 with an effective photospheric temperature of 4,985 K, a radius of 0.815 R☉, a mass of 0.849 M☉, an estimated bolometric luminosity of 0.368 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.8 Gyr and a metallicity of [Fe/H] = 0.25 dex (metal-rich relative to the Sun). From Earth, HATS-7 shines at apparent V-band magnitude 13.347 (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-7 |
| Spectral Type | K2 |
| Effective Temp (Teff) | 4,985 K |
| Stellar Radius | 0.8150 R☉ |
| Stellar Mass | 0.8490 M☉ |
| Bolometric Luminosity | 0.368 L☉ |
| Metallicity [Fe/H] | 0.250 dex |
| Stellar Age | 7.800 Gyr |
| Apparent Magnitude | V: 13.347 · G: 13.050 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.040120 AU |
| Orbital Period | 3.185 days |
| Mean Orbital Velocity | 137 km/s |
| Orbital Eccentricity (e) | 0.17000 |
| Orbital Inclination (i) | 87.9200° |
| Mean Bulk Density | 0.84 g/cm³ (27.5 km/s vesc) |
| Insolation Flux | 211.6178 S⊕ (~288,012 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 785.100 LY (240.707 pc) |