HATS-5 b
Astrophysical Synthesis & Habitability Characterization
HATS-5 b is a confirmed gas giant exoplanet orbiting the star HATS-5, located approximately 803.6 light-years (246.38 parsecs) from the Solar System. First announced in 2014 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 1.1579% across the stellar disk), this world measures 10.223 Earth radii (0.91 Jupiter radii) and has a measured mass of 75.323 Earth masses (0.24 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.39 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.72 g⊕ (7.06 m/s²), and an escape velocity of 30.4 km/s.
In its orbital architecture around HATS-5, HATS-5 b completes one full revolution every 4.763 Earth days at a semi-major axis of 0.0542 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 123.8 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.019 (ranging from 0.0532 AU at periapsis to 0.0552 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1025 K (+752°C / +1386°F) and receiving 183.24 S⊕ (~249,389 W/m²), HATS-5 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-5 is classified as a solar-type yellow star of spectral type G with an effective photospheric temperature of 5,304 K, a radius of 0.871 R☉, a mass of 0.936 M☉, an estimated bolometric luminosity of 0.539 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.6 Gyr and a metallicity of [Fe/H] = 0.19 dex (metal-rich relative to the Sun). From Earth, HATS-5 shines at apparent V-band magnitude 12.598 (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-5 |
| Spectral Type | G |
| Effective Temp (Teff) | 5,304 K |
| Stellar Radius | 0.8710 R☉ |
| Stellar Mass | 0.9360 M☉ |
| Bolometric Luminosity | 0.539 L☉ |
| Metallicity [Fe/H] | 0.190 dex |
| Stellar Age | 3.600 Gyr |
| Apparent Magnitude | V: 12.598 · G: 12.429 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.054200 AU |
| Orbital Period | 4.763 days |
| Mean Orbital Velocity | 123.8 km/s |
| Orbital Eccentricity (e) | 0.01900 |
| Orbital Inclination (i) | 89.3000° |
| Mean Bulk Density | 0.39 g/cm³ (30.4 km/s vesc) |
| Insolation Flux | 183.2395 S⊕ (~249,389 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 803.600 LY (246.384 pc) |