HATS-57 b
Astrophysical Synthesis & Habitability Characterization
HATS-57 b is a confirmed gas giant exoplanet orbiting the star HATS-57, located approximately 911.6 light-years (279.49 parsecs) from the Solar System. First announced in 2019 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 1.4865% across the stellar disk), this world measures 12.767 Earth radii (1.14 Jupiter radii) and has a measured mass of 1000.211 Earth masses (3.15 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.65 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.14 g⊕ (60.21 m/s²), and an escape velocity of 99 km/s.
In its orbital architecture around HATS-57, HATS-57 b completes one full revolution every 2.351 Earth days at a semi-major axis of 0.03493 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 161.7 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.028 (ranging from 0.034 AU at periapsis to 0.0359 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1413 K (+1140°C / +2084°F) and receiving 570.23 S⊕ (~776,087 W/m²), HATS-57 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-57 is classified as a stellar host with an effective photospheric temperature of 5,587 K, a radius of 0.96 R☉, a mass of 1.026 M☉, an estimated bolometric luminosity of 0.806 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.5 Gyr and a metallicity of [Fe/H] = 0.268 dex (metal-rich relative to the Sun). From Earth, HATS-57 shines at apparent V-band magnitude 12.333 (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-57 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,587 K |
| Stellar Radius | 0.9600 R☉ |
| Stellar Mass | 1.0260 M☉ |
| Bolometric Luminosity | 0.806 L☉ |
| Metallicity [Fe/H] | 0.268 dex |
| Stellar Age | 2.500 Gyr |
| Apparent Magnitude | V: 12.333 · G: 12.182 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.034930 AU |
| Orbital Period | 2.351 days |
| Mean Orbital Velocity | 161.7 km/s |
| Orbital Eccentricity (e) | 0.02800 |
| Orbital Inclination (i) | 87.8800° |
| Mean Bulk Density | 2.65 g/cm³ (99 km/s vesc) |
| Insolation Flux | 570.2330 S⊕ (~776,087 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 911.600 LY (279.485 pc) |