TOI-5218 b
Astrophysical Synthesis & Habitability Characterization
TOI-5218 b is a confirmed gas giant exoplanet orbiting the star TOI-5218, located approximately 1231.2 light-years (377.48 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 1.6302% across the stellar disk), this world measures 9.86 Earth radii (0.88 Jupiter radii) and has a measured mass of 657 Earth masses (2.07 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.78 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.76 g⊕ (66.29 m/s²), and an escape velocity of 91.3 km/s.
In its orbital architecture around TOI-5218, TOI-5218 b completes one full revolution every 4.291 Earth days at a semi-major axis of 0.0469 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 118.9 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 783 K (+510°C / +950°F) and receiving 62.00 S⊕ (~84,382 W/m²), TOI-5218 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5218 is classified as a stellar host with an effective photospheric temperature of 4,230 K, a radius of 0.708 R☉, a mass of 0.739 M☉, an estimated bolometric luminosity of 0.144 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.7 Gyr and a metallicity of [Fe/H] = 0.41 dex (metal-rich relative to the Sun). From Earth, TOI-5218 shines at apparent V-band magnitude 16.044 (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: Transiting Exoplanet Survey Satellite (TESS) · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-5218 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,230 K |
| Stellar Radius | 0.7080 R☉ |
| Stellar Mass | 0.7390 M☉ |
| Bolometric Luminosity | 0.144 L☉ |
| Metallicity [Fe/H] | 0.410 dex |
| Stellar Age | 6.700 Gyr |
| Apparent Magnitude | V: 16.044 · G: 15.450 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.046900 AU |
| Orbital Period | 4.291 days |
| Mean Orbital Velocity | 118.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.4100° |
| Mean Bulk Density | 3.78 g/cm³ (91.3 km/s vesc) |
| Insolation Flux | 62.0000 S⊕ (~84,382 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1231.200 LY (377.483 pc) |