NGTS-31 b
Astrophysical Synthesis & Habitability Characterization
NGTS-31 b is a confirmed gas giant exoplanet orbiting the star NGTS-31, located approximately 1622.2 light-years (497.38 parsecs) from the Solar System. First announced in 2025 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.9471% across the stellar disk), this world measures 18.046 Earth radii (1.61 Jupiter radii) and has a measured mass of 355.968 Earth masses (1.12 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.33 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 49.7 km/s.
In its orbital architecture around NGTS-31, NGTS-31 b completes one full revolution every 4.163 Earth days at a semi-major axis of 0.064 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 167.3 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 1410 K (+1137°C / +2079°F) and receiving 643.00 S⊕ (~875,123 W/m²), NGTS-31 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star NGTS-31 is classified as a stellar host with an effective photospheric temperature of 5,710 K, a radius of 1.7 R☉, a mass of 0.96 M☉, an estimated bolometric luminosity of 2.756 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.97 Gyr and a metallicity of [Fe/H] = 0 dex (near-solar heavy-element abundance). From Earth, NGTS-31 shines at apparent V-band magnitude 13.519 (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-31 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,710 K |
| Stellar Radius | 1.7000 R☉ |
| Stellar Mass | 0.9600 M☉ |
| Bolometric Luminosity | 2.756 L☉ |
| Metallicity [Fe/H] | 0.000 dex |
| Stellar Age | 9.970 Gyr |
| Apparent Magnitude | V: 13.519 · G: 13.303 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.064000 AU |
| Orbital Period | 4.163 days |
| Mean Orbital Velocity | 167.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 85.6000° |
| Mean Bulk Density | 0.33 g/cm³ (49.7 km/s vesc) |
| Insolation Flux | 643.0000 S⊕ (~875,123 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1622.200 LY (497.376 pc) |