NGTS-24 b
Astrophysical Synthesis & Habitability Characterization
NGTS-24 b is a confirmed gas giant exoplanet orbiting the star NGTS-24, located approximately 2227.8 light-years (683.06 parsecs) from the Solar System. First announced in 2022 by Next-Generation Transit Survey (NGTS) using the Transit detection technique (producing an estimated primary transit depth of 0.5787% across the stellar disk), this world measures 13.608 Earth radii (1.21 Jupiter radii) and has a measured mass of 165.271 Earth masses (0.52 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.36 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.89 g⊕ (8.73 m/s²), and an escape velocity of 39 km/s.
In its orbital architecture around NGTS-24, NGTS-24 b completes one full revolution every 3.468 Earth days at a semi-major axis of 0.0479 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 150.3 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 1499 K (+1226°C / +2239°F) and receiving 391.83 S⊕ (~533,281 W/m²), NGTS-24 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star NGTS-24 is classified as a solar-type yellow star of spectral type G2 IV with an effective photospheric temperature of 5,820 K, a radius of 1.64 R☉, a mass of 1.26 M☉, an estimated bolometric luminosity of 2.769 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.77 Gyr and a metallicity of [Fe/H] = 0.27 dex (metal-rich relative to the Sun). From Earth, NGTS-24 shines at apparent V-band magnitude 13.214 (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: Next-Generation Transit Survey (NGTS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | NGTS-24 |
| Spectral Type | G2 IV |
| Effective Temp (Teff) | 5,820 K |
| Stellar Radius | 1.6400 R☉ |
| Stellar Mass | 1.2600 M☉ |
| Bolometric Luminosity | 2.769 L☉ |
| Metallicity [Fe/H] | 0.270 dex |
| Stellar Age | 4.770 Gyr |
| Apparent Magnitude | V: 13.214 · G: 13.053 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047900 AU |
| Orbital Period | 3.468 days |
| Mean Orbital Velocity | 150.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 82.6100° |
| Mean Bulk Density | 0.36 g/cm³ (39 km/s vesc) |
| Insolation Flux | 391.8300 S⊕ (~533,281 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2227.800 LY (683.062 pc) |