Qatar-8 b
Astrophysical Synthesis & Habitability Characterization
Qatar-8 b is a confirmed gas giant exoplanet orbiting the star Qatar-8, located approximately 918.1 light-years (281.5 parsecs) from the Solar System. First announced in 2019 by Qatar using the Transit detection technique (producing an estimated primary transit depth of 1.0085% across the stellar disk), this world measures 14.404 Earth radii (1.29 Jupiter radii) and has a measured mass of 117.915 Earth masses (0.37 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.22 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.57 g⊕ (5.59 m/s²), and an escape velocity of 32 km/s.
In its orbital architecture around Qatar-8, Qatar-8 b completes one full revolution every 3.715 Earth days at a semi-major axis of 0.0474 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 138.8 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 1457 K (+1184°C / +2163°F) and receiving 698.15 S⊕ (~950,179 W/m²), Qatar-8 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Qatar-8 is classified as a solar-type yellow star of spectral type G0 V with an effective photospheric temperature of 5,738 K, a radius of 1.315 R☉, a mass of 1.029 M☉, an estimated bolometric luminosity of 1.682 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.3 Gyr and a metallicity of [Fe/H] = 0.025 dex (near-solar heavy-element abundance). From Earth, Qatar-8 shines at apparent V-band magnitude 11.71 (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: Qatar · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Qatar-8 |
| Spectral Type | G0 V |
| Effective Temp (Teff) | 5,738 K |
| Stellar Radius | 1.3150 R☉ |
| Stellar Mass | 1.0290 M☉ |
| Bolometric Luminosity | 1.682 L☉ |
| Metallicity [Fe/H] | 0.025 dex |
| Stellar Age | 8.300 Gyr |
| Apparent Magnitude | V: 11.710 · G: 11.349 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047400 AU |
| Orbital Period | 3.715 days |
| Mean Orbital Velocity | 138.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.2900° |
| Mean Bulk Density | 0.22 g/cm³ (32 km/s vesc) |
| Insolation Flux | 698.1480 S⊕ (~950,179 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 918.100 LY (281.498 pc) |