CoRoT-18 b
Astrophysical Synthesis & Habitability Characterization
CoRoT-18 b is a confirmed gas giant exoplanet orbiting the star CoRoT-18, located approximately 2494.7 light-years (764.89 parsecs) from the Solar System. First announced in 2011 by CoRoT using the Transit detection technique (producing an estimated primary transit depth of 1.8113% across the stellar disk), this world measures 14.68 Earth radii (1.31 Jupiter radii) and has a measured mass of 1102.82 Earth masses (3.47 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.92 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 5.12 g⊕ (50.21 m/s²), and an escape velocity of 97 km/s.
In its orbital architecture around CoRoT-18, CoRoT-18 b completes one full revolution every 1.9 Earth days at a semi-major axis of 0.0295 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). Its moderate orbital eccentricity of e = 0.08 carries the world between 0.0271 AU at periapsis and 0.0319 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1550 K (+1277°C / +2331°F) and receiving 823.70 S⊕ (~1,121,057 W/m²), CoRoT-18 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star CoRoT-18 is classified as a solar-type yellow star of spectral type G9 V with an effective photospheric temperature of 5,440 K, a radius of 1 R☉, a mass of 0.95 M☉, an estimated bolometric luminosity of 0.786 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.6 Gyr and a metallicity of [Fe/H] = -0.1 dex (near-solar heavy-element abundance). From Earth, CoRoT-18 shines at apparent V-band magnitude 14.868 (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: CoRoT · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | CoRoT-18 |
| Spectral Type | G9 V |
| Effective Temp (Teff) | 5,440 K |
| Stellar Radius | 1.0000 R☉ |
| Stellar Mass | 0.9500 M☉ |
| Bolometric Luminosity | 0.786 L☉ |
| Metallicity [Fe/H] | -0.100 dex |
| Stellar Age | 0.600 Gyr |
| Apparent Magnitude | V: 14.868 · G: 14.801 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.029500 AU |
| Orbital Period | 1.9 days |
| Mean Orbital Velocity | 168.9 km/s |
| Orbital Eccentricity (e) | 0.08000 |
| Orbital Inclination (i) | 86.5000° |
| Mean Bulk Density | 1.92 g/cm³ (97 km/s vesc) |
| Insolation Flux | 823.7009 S⊕ (~1,121,057 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2494.700 LY (764.889 pc) |