HATS-58 A b

Astrophysical Synthesis & Habitability Characterization

HATS-58 A b is a confirmed gas giant exoplanet orbiting the star HATS-58 A, located approximately 1316.3 light-years (403.59 parsecs) from the Solar System. First announced in 2019 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.6166% across the stellar disk), this world measures 12.274 Earth radii (1.1 Jupiter radii) and has a measured mass of 327.365 Earth masses (1.03 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.98 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.17 g⊕ (21.28 m/s²), and an escape velocity of 57.8 km/s.

In its orbital architecture around HATS-58 A, HATS-58 A b completes one full revolution every 4.218 Earth days at a semi-major axis of 0.05798 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 149.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.168 carries the world between 0.0482 AU at periapsis and 0.0677 AU at apoapsis, driving measurable seasonal insolation cycles.

⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1721 K (+1448°C / +2638°F) and receiving 382.71 S⊕ (~520,869 W/m²), HATS-58 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.

The host star HATS-58 A is classified as a stellar host with an effective photospheric temperature of 7,175 K, a radius of 1.433 R☉, a mass of 1.461 M☉, an estimated bolometric luminosity of 4.883 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.31 Gyr. From Earth, HATS-58 A shines at apparent V-band magnitude 11.572 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere.

Discovery Facility: HATSouth · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).