Qatar-4 b
Astrophysical Synthesis & Habitability Characterization
Qatar-4 b is a confirmed gas giant exoplanet orbiting the star Qatar-4, located approximately 1073.2 light-years (329.04 parsecs) from the Solar System. First announced in 2017 by Qatar using the Transit detection technique (producing an estimated primary transit depth of 1.8873% across the stellar disk), this world measures 12.722 Earth radii (1.13 Jupiter radii) and has a measured mass of 1938.763 Earth masses (6.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 5.19 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 11.98 g⊕ (117.48 m/s²), and an escape velocity of 138.1 km/s.
In its orbital architecture around Qatar-4, Qatar-4 b completes one full revolution every 1.805 Earth days at a semi-major axis of 0.02803 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 168.9 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 1385 K (+1112°C / +2034°F) and receiving 614.00 S⊕ (~835,654 W/m²), Qatar-4 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star Qatar-4 is classified as an orange K-type star of spectral type K1 V with an effective photospheric temperature of 5,215 K, a radius of 0.849 R☉, a mass of 0.896 M☉, an estimated bolometric luminosity of 0.478 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.17 Gyr and a metallicity of [Fe/H] = 0.103 dex (metal-rich relative to the Sun). From Earth, Qatar-4 shines at apparent V-band magnitude 13.574 (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-4 |
| Spectral Type | K1 V |
| Effective Temp (Teff) | 5,215 K |
| Stellar Radius | 0.8490 R☉ |
| Stellar Mass | 0.8960 M☉ |
| Bolometric Luminosity | 0.478 L☉ |
| Metallicity [Fe/H] | 0.103 dex |
| Stellar Age | 0.170 Gyr |
| Apparent Magnitude | V: 13.574 · G: 13.411 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.028030 AU |
| Orbital Period | 1.805 days |
| Mean Orbital Velocity | 168.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.5000° |
| Mean Bulk Density | 5.19 g/cm³ (138.1 km/s vesc) |
| Insolation Flux | 614.0000 S⊕ (~835,654 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1073.200 LY (329.036 pc) |