TOI-2818 b
Astrophysical Synthesis & Habitability Characterization
TOI-2818 b is a confirmed gas giant exoplanet orbiting the star TOI-2818, located approximately 1019.8 light-years (312.67 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 1.2989% across the stellar disk), this world measures 15.278 Earth radii (1.36 Jupiter radii) and has a measured mass of 225.658 Earth masses (0.71 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.35 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.97 g⊕ (9.51 m/s²), and an escape velocity of 43 km/s.
In its orbital architecture around TOI-2818, TOI-2818 b completes one full revolution every 4.04 Earth days at a semi-major axis of 0.0493 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 132.8 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 1376 K (+1103°C / +2017°F) and receiving 598.00 S⊕ (~813,878 W/m²), TOI-2818 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-2818 is classified as a stellar host with an effective photospheric temperature of 5,721 K, a radius of 1.229 R☉, a mass of 0.977 M☉, an estimated bolometric luminosity of 1.452 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.5 Gyr and a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, TOI-2818 shines at apparent V-band magnitude 11.937 (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 | TOI-2818 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,721 K |
| Stellar Radius | 1.2290 R☉ |
| Stellar Mass | 0.9770 M☉ |
| Bolometric Luminosity | 1.452 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | 9.500 Gyr |
| Apparent Magnitude | V: 11.937 · G: 11.837 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.049300 AU |
| Orbital Period | 4.04 days |
| Mean Orbital Velocity | 132.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.7300° |
| Mean Bulk Density | 0.35 g/cm³ (43 km/s vesc) |
| Insolation Flux | 598.0000 S⊕ (~813,878 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1019.800 LY (312.674 pc) |