NGTS-1 b
Astrophysical Synthesis & Habitability Characterization
NGTS-1 b is a confirmed gas giant exoplanet orbiting the star NGTS-1, located approximately 711.4 light-years (218.12 parsecs) from the Solar System. First announced in 2017 by Next-Generation Transit Survey (NGTS) using the Transit detection technique (producing an estimated primary transit depth of 5.6895% across the stellar disk), this world measures 14.908 Earth radii (1.33 Jupiter radii) and has a measured mass of 258.078 Earth masses (0.81 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 46.5 km/s.
In its orbital architecture around NGTS-1, NGTS-1 b completes one full revolution every 2.647 Earth days at a semi-major axis of 0.0326 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 134 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.016 (ranging from 0.0321 AU at periapsis to 0.0331 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 790 K (+517°C / +963°F) and receiving 65.30 S⊕ (~88,873 W/m²), NGTS-1 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star NGTS-1 is classified as a low-mass red dwarf of spectral type M0.5 with an effective photospheric temperature of 3,916 K, a radius of 0.573 R☉, a mass of 0.617 M☉, an estimated bolometric luminosity of 0.069 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, NGTS-1 shines at apparent V-band magnitude 15.667 (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-1 |
| Spectral Type | M0.5 |
| Effective Temp (Teff) | 3,916 K |
| Stellar Radius | 0.5730 R☉ |
| Stellar Mass | 0.6170 M☉ |
| Bolometric Luminosity | 0.069 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 15.667 · G: 14.866 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.032600 AU |
| Orbital Period | 2.647 days |
| Mean Orbital Velocity | 134 km/s |
| Orbital Eccentricity (e) | 0.01600 |
| Orbital Inclination (i) | 85.2700° |
| Mean Bulk Density | 0.43 g/cm³ (46.5 km/s vesc) |
| Insolation Flux | 65.3000 S⊕ (~88,873 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 711.400 LY (218.121 pc) |