HATS-33 b
Astrophysical Synthesis & Habitability Characterization
HATS-33 b is a confirmed gas giant exoplanet orbiting the star HATS-33, located approximately 810.4 light-years (248.46 parsecs) from the Solar System. First announced in 2016 by HATSouth using the Transit detection technique (producing an estimated primary transit depth of 1.5296% across the stellar disk), this world measures 13.787 Earth radii (1.23 Jupiter radii) and has a measured mass of 378.853 Earth masses (1.19 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.8 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.99 g⊕ (19.52 m/s²), and an escape velocity of 58.6 km/s.
In its orbital architecture around HATS-33, HATS-33 b completes one full revolution every 2.55 Earth days at a semi-major axis of 0.03727 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 159 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.08 carries the world between 0.0343 AU at periapsis and 0.0403 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1429 K (+1156°C / +2113°F) and receiving 757.13 S⊕ (~1,030,452 W/m²), HATS-33 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HATS-33 is classified as a stellar host with an effective photospheric temperature of 5,659 K, a radius of 1.022 R☉, a mass of 1.062 M☉, an estimated bolometric luminosity of 0.961 L☉. Stellar evolution modeling indicates an estimated stellar age of 3 Gyr and a metallicity of [Fe/H] = 0.29 dex (metal-rich relative to the Sun). From Earth, HATS-33 shines at apparent V-band magnitude 11.91 (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-33 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,659 K |
| Stellar Radius | 1.0220 R☉ |
| Stellar Mass | 1.0620 M☉ |
| Bolometric Luminosity | 0.961 L☉ |
| Metallicity [Fe/H] | 0.290 dex |
| Stellar Age | 3.000 Gyr |
| Apparent Magnitude | V: 11.910 · G: 11.708 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.037270 AU |
| Orbital Period | 2.55 days |
| Mean Orbital Velocity | 159 km/s |
| Orbital Eccentricity (e) | 0.08000 |
| Orbital Inclination (i) | 87.6200° |
| Mean Bulk Density | 0.8 g/cm³ (58.6 km/s vesc) |
| Insolation Flux | 757.1284 S⊕ (~1,030,452 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 810.400 LY (248.460 pc) |