HATS-17 b
Astrophysical Synthesis & Habitability Characterization
HATS-17 b is a confirmed gas giant exoplanet orbiting the star HATS-17, located approximately 1305.7 light-years (400.33 parsecs) from the Solar System. First announced in 2016 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.5356% across the stellar disk), this world measures 8.709 Earth radii (0.78 Jupiter radii) and has a measured mass of 425.257 Earth masses (1.34 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.55 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 5.61 g⊕ (55.02 m/s²), and an escape velocity of 78.2 km/s.
In its orbital architecture around HATS-17, HATS-17 b completes one full revolution every 16.255 Earth days at a semi-major axis of 0.1308 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 87.5 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.029 (ranging from 0.127 AU at periapsis to 0.1346 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 814 K (+541°C / +1006°F) and receiving 72.70 S⊕ (~98,945 W/m²), HATS-17 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-17 is classified as a solar-type yellow star of spectral type G V with an effective photospheric temperature of 5,846 K, a radius of 1.091 R☉, a mass of 1.131 M☉, an estimated bolometric luminosity of 1.247 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.1 Gyr and a metallicity of [Fe/H] = 0.3 dex (metal-rich relative to the Sun). From Earth, HATS-17 shines at apparent V-band magnitude 12.402 (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-17 |
| Spectral Type | G V |
| Effective Temp (Teff) | 5,846 K |
| Stellar Radius | 1.0910 R☉ |
| Stellar Mass | 1.1310 M☉ |
| Bolometric Luminosity | 1.247 L☉ |
| Metallicity [Fe/H] | 0.300 dex |
| Stellar Age | 2.100 Gyr |
| Apparent Magnitude | V: 12.402 · G: 12.218 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.130800 AU |
| Orbital Period | 16.255 days |
| Mean Orbital Velocity | 87.5 km/s |
| Orbital Eccentricity (e) | 0.02900 |
| Orbital Inclination (i) | 89.0800° |
| Mean Bulk Density | 3.55 g/cm³ (78.2 km/s vesc) |
| Insolation Flux | 72.7000 S⊕ (~98,945 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1305.700 LY (400.331 pc) |