NGTS-5 b
Astrophysical Synthesis & Habitability Characterization
NGTS-5 b is a confirmed gas giant exoplanet orbiting the star NGTS-5, located approximately 1000.6 light-years (306.78 parsecs) from the Solar System. First announced in 2019 by Next-Generation Transit Survey (NGTS) using the Transit detection technique (producing an estimated primary transit depth of 2.4953% across the stellar disk), this world measures 12.733 Earth radii (1.14 Jupiter radii) and has a measured mass of 72.783 Earth masses (0.23 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.19 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.45 g⊕ (4.41 m/s²), and an escape velocity of 26.7 km/s.
In its orbital architecture around NGTS-5, NGTS-5 b completes one full revolution every 3.357 Earth days at a semi-major axis of 0.0382 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 123.8 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 952 K (+679°C / +1254°F) and receiving 101.25 S⊕ (~137,805 W/m²), NGTS-5 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star NGTS-5 is classified as an orange K-type star of spectral type K2 V with an effective photospheric temperature of 4,987 K, a radius of 0.739 R☉, a mass of 0.661 M☉, an estimated bolometric luminosity of 0.303 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, NGTS-5 shines at apparent V-band magnitude 13.789 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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-5 |
| Spectral Type | K2 V |
| Effective Temp (Teff) | 4,987 K |
| Stellar Radius | 0.7390 R☉ |
| Stellar Mass | 0.6610 M☉ |
| Bolometric Luminosity | 0.303 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.789 · G: 13.526 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.038200 AU |
| Orbital Period | 3.357 days |
| Mean Orbital Velocity | 123.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 86.6000° |
| Mean Bulk Density | 0.19 g/cm³ (26.7 km/s vesc) |
| Insolation Flux | 101.2530 S⊕ (~137,805 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1000.600 LY (306.779 pc) |