HATS-64 b
Astrophysical Synthesis & Habitability Characterization
HATS-64 b is a confirmed gas giant exoplanet orbiting the star HATS-64, located approximately 3523 light-years (1080.15 parsecs) from the Solar System. First announced in 2018 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 0.6668% across the stellar disk), this world measures 18.82 Earth radii (1.68 Jupiter radii) and has a measured mass of 305.117 Earth masses (0.96 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.25 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.86 g⊕ (8.43 m/s²), and an escape velocity of 45 km/s.
In its orbital architecture around HATS-64, HATS-64 b completes one full revolution every 4.909 Earth days at a semi-major axis of 0.06562 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 145.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.151 carries the world between 0.0557 AU at periapsis and 0.0755 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1793 K (+1520°C / +2768°F) and receiving 1,711.00 S⊕ (~2,328,671 W/m²), HATS-64 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-64 is classified as a stellar host with an effective photospheric temperature of 6,554 K, a radius of 2.113 R☉, a mass of 1.564 M☉, an estimated bolometric luminosity of 7.391 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.861 Gyr and a metallicity of [Fe/H] = 0.22 dex (metal-rich relative to the Sun). From Earth, HATS-64 shines at apparent V-band magnitude 13.045 (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-64 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,554 K |
| Stellar Radius | 2.1130 R☉ |
| Stellar Mass | 1.5640 M☉ |
| Bolometric Luminosity | 7.391 L☉ |
| Metallicity [Fe/H] | 0.220 dex |
| Stellar Age | 1.861 Gyr |
| Apparent Magnitude | V: 13.045 · G: 12.839 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.065620 AU |
| Orbital Period | 4.909 days |
| Mean Orbital Velocity | 145.4 km/s |
| Orbital Eccentricity (e) | 0.15100 |
| Orbital Inclination (i) | 87.2400° |
| Mean Bulk Density | 0.25 g/cm³ (45 km/s vesc) |
| Insolation Flux | 1711.0000 S⊕ (~2,328,671 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 3523.000 LY (1080.150 pc) |