NGTS-33 b
Astrophysical Synthesis & Habitability Characterization
NGTS-33 b is a confirmed gas giant exoplanet orbiting the star NGTS-33, located approximately 1428.1 light-years (437.86 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 1.3144% across the stellar disk), this world measures 18.383 Earth radii (1.64 Jupiter radii) and has a measured mass of 1153.717 Earth masses (3.63 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.02 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.41 g⊕ (33.44 m/s²), and an escape velocity of 88.6 km/s.
In its orbital architecture around NGTS-33, NGTS-33 b completes one full revolution every 2.828 Earth days at a semi-major axis of 0.048 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 184.7 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 1991 K (+1718°C / +3124°F) and receiving 2,620.00 S⊕ (~3,565,820 W/m²), NGTS-33 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star NGTS-33 is classified as a stellar host with an effective photospheric temperature of 7,437 K, a radius of 1.47 R☉, a mass of 1.6 M☉, an estimated bolometric luminosity of 5.931 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.03 Gyr and a metallicity of [Fe/H] = -0.11 dex (metal-poor relative to the Sun). From Earth, NGTS-33 shines at apparent V-band magnitude 11.604 (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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | NGTS-33 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 7,437 K |
| Stellar Radius | 1.4700 R☉ |
| Stellar Mass | 1.6000 M☉ |
| Bolometric Luminosity | 5.931 L☉ |
| Metallicity [Fe/H] | -0.110 dex |
| Stellar Age | 0.030 Gyr |
| Apparent Magnitude | V: 11.604 · G: 11.398 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048000 AU |
| Orbital Period | 2.828 days |
| Mean Orbital Velocity | 184.7 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 83.9400° |
| Mean Bulk Density | 1.02 g/cm³ (88.6 km/s vesc) |
| Insolation Flux | 2620.0000 S⊕ (~3,565,820 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1428.100 LY (437.855 pc) |