HAT-P-33 b
Astrophysical Synthesis & Habitability Characterization
HAT-P-33 b is a confirmed gas giant exoplanet orbiting the star HAT-P-33, located approximately 1291.9 light-years (396.11 parsecs) from the Solar System. First announced in 2011 by HATNet using the Transit detection technique (producing an estimated primary transit depth of 1.128% across the stellar disk), this world measures 20.737 Earth radii (1.85 Jupiter radii) and has a measured mass of 292.404 Earth masses (0.92 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.18 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.68 g⊕ (6.67 m/s²), and an escape velocity of 42 km/s.
In its orbital architecture around HAT-P-33, HAT-P-33 b completes one full revolution every 3.474 Earth days at a semi-major axis of 0.04995 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 156.4 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1782 K (+1509°C / +2748°F) and receiving 1,701.38 S⊕ (~2,315,578 W/m²), HAT-P-33 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star HAT-P-33 is classified as a warm F-type star of spectral type F4 with an effective photospheric temperature of 6,446 K, a radius of 1.79 R☉, a mass of 1.82 M☉, an estimated bolometric luminosity of 4.963 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.3 Gyr and a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, HAT-P-33 shines at apparent V-band magnitude 11.032 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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: HATNet · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HAT-P-33 |
| Spectral Type | F4 |
| Effective Temp (Teff) | 6,446 K |
| Stellar Radius | 1.7900 R☉ |
| Stellar Mass | 1.8200 M☉ |
| Bolometric Luminosity | 4.963 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | 2.300 Gyr |
| Apparent Magnitude | V: 11.032 · G: 11.024 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049950 AU |
| Orbital Period | 3.474 days |
| Mean Orbital Velocity | 156.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.2000° |
| Mean Bulk Density | 0.18 g/cm³ (42 km/s vesc) |
| Insolation Flux | 1701.3800 S⊕ (~2,315,578 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1291.900 LY (396.110 pc) |