NGTS-2 b
Astrophysical Synthesis & Habitability Characterization
NGTS-2 b is a confirmed gas giant exoplanet orbiting the star NGTS-2, located approximately 1162.4 light-years (356.39 parsecs) from the Solar System. First announced in 2018 by Next-Generation Transit Survey (NGTS) using the Transit detection technique (producing an estimated primary transit depth of 0.9274% across the stellar disk), this world measures 17.878 Earth radii (1.59 Jupiter radii) and has a measured mass of 235.194 Earth masses (0.74 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.23 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.74 g⊕ (7.26 m/s²), and an escape velocity of 40.6 km/s.
In its orbital architecture around NGTS-2, NGTS-2 b completes one full revolution every 4.511 Earth days at a semi-major axis of 0.063 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 151.9 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 1468 K (+1195°C / +2183°F) and receiving 1,085.35 S⊕ (~1,477,161 W/m²), NGTS-2 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star NGTS-2 is classified as a warm F-type star of spectral type F5 V with an effective photospheric temperature of 6,478 K, a radius of 1.702 R☉, a mass of 1.64 M☉, an estimated bolometric luminosity of 4.577 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.17 Gyr and a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, NGTS-2 shines at apparent V-band magnitude 10.789 (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-2 |
| Spectral Type | F5 V |
| Effective Temp (Teff) | 6,478 K |
| Stellar Radius | 1.7020 R☉ |
| Stellar Mass | 1.6400 M☉ |
| Bolometric Luminosity | 4.577 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | 2.170 Gyr |
| Apparent Magnitude | V: 10.789 · G: 10.861 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.063000 AU |
| Orbital Period | 4.511 days |
| Mean Orbital Velocity | 151.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.5000° |
| Mean Bulk Density | 0.23 g/cm³ (40.6 km/s vesc) |
| Insolation Flux | 1085.3500 S⊕ (~1,477,161 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1162.400 LY (356.391 pc) |