NGTS-20 b
Astrophysical Synthesis & Habitability Characterization
NGTS-20 b is a confirmed gas giant exoplanet orbiting the star NGTS-20, located approximately 1248.8 light-years (382.9 parsecs) from the Solar System. First announced in 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.3816% across the stellar disk), this world measures 11.994 Earth radii (1.07 Jupiter radii) and has a measured mass of 947.129 Earth masses (2.98 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.03 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.58 g⊕ (64.53 m/s²), and an escape velocity of 99.4 km/s.
In its orbital architecture around NGTS-20, NGTS-20 b completes one full revolution every 54.189 Earth days at a semi-major axis of 0.313 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 62.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.432, swinging from 0.1778 AU at periapsis out to 0.4482 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 688 K (+415°C / +779°F) and receiving 6.76 S⊕ (~9,206 W/m²), NGTS-20 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star NGTS-20 is classified as a solar-type yellow star of spectral type G1 IV with an effective photospheric temperature of 5,980 K, a radius of 1.78 R☉, a mass of 1.47 M☉, an estimated bolometric luminosity of 3.635 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.1 Gyr and a metallicity of [Fe/H] = 0.15 dex (metal-rich relative to the Sun). From Earth, NGTS-20 shines at apparent V-band magnitude 11.233 (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-20 |
| Spectral Type | G1 IV |
| Effective Temp (Teff) | 5,980 K |
| Stellar Radius | 1.7800 R☉ |
| Stellar Mass | 1.4700 M☉ |
| Bolometric Luminosity | 3.635 L☉ |
| Metallicity [Fe/H] | 0.150 dex |
| Stellar Age | 4.100 Gyr |
| Apparent Magnitude | V: 11.233 · G: 11.031 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.313000 AU |
| Orbital Period | 54.189 days |
| Mean Orbital Velocity | 62.8 km/s |
| Orbital Eccentricity (e) | 0.43200 |
| Orbital Inclination (i) | 88.4000° |
| Mean Bulk Density | 3.03 g/cm³ (99.4 km/s vesc) |
| Insolation Flux | 6.7645 S⊕ (~9,206 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1248.800 LY (382.898 pc) |