HATS-74 A b
Astrophysical Synthesis & Habitability Characterization
HATS-74 A b is a confirmed gas giant exoplanet orbiting the star HATS-74 A, located approximately 976.5 light-years (299.39 parsecs) from the Solar System. First announced in 2021 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 3.3925% across the stellar disk), this world measures 11.568 Earth radii (1.03 Jupiter radii) and has a measured mass of 464.029 Earth masses (1.46 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.65 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.47 g⊕ (34.03 m/s²), and an escape velocity of 70.8 km/s.
In its orbital architecture around HATS-74 A, HATS-74 A b completes one full revolution every 1.732 Earth days at a semi-major axis of 0.02384 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 149.8 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.044 (ranging from 0.0228 AU at periapsis to 0.0249 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 895 K (+622°C / +1152°F) and receiving 106.90 S⊕ (~145,491 W/m²), HATS-74 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-74 A is classified as a stellar host with an effective photospheric temperature of 3,777 K, a radius of 0.5758 R☉, a mass of 0.601 M☉, an estimated bolometric luminosity of 0.061 L☉. Stellar evolution modeling indicates an estimated stellar age of 11 Gyr and a metallicity of [Fe/H] = 0.514 dex (metal-rich relative to the Sun). From Earth, HATS-74 A shines at apparent V-band magnitude 17.26 (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-74 A |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,777 K |
| Stellar Radius | 0.5758 R☉ |
| Stellar Mass | 0.6010 M☉ |
| Bolometric Luminosity | 0.061 L☉ |
| Metallicity [Fe/H] | 0.514 dex |
| Stellar Age | 11.000 Gyr |
| Apparent Magnitude | V: 17.260 · G: 15.984 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.023840 AU |
| Orbital Period | 1.732 days |
| Mean Orbital Velocity | 149.8 km/s |
| Orbital Eccentricity (e) | 0.04400 |
| Orbital Inclination (i) | 87.3900° |
| Mean Bulk Density | 1.65 g/cm³ (70.8 km/s vesc) |
| Insolation Flux | 106.9000 S⊕ (~145,491 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 976.500 LY (299.389 pc) |