TOI-813 b
Astrophysical Synthesis & Habitability Characterization
TOI-813 b is a confirmed gas giant exoplanet orbiting the star TOI-813, located approximately 858.3 light-years (263.15 parsecs) from the Solar System. First announced in 2020 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1006% across the stellar disk), this world measures 6.71 Earth radii (0.6 Jupiter radii) and has a measured mass of 36.4 Earth masses (0.11 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.66 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.81 g⊕ (7.94 m/s²), and an escape velocity of 26.1 km/s.
In its orbital architecture around TOI-813, TOI-813 b completes one full revolution every 83.891 Earth days at a semi-major axis of 0.423 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 54.9 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 610 K (+337°C / +639°F) and receiving 23.10 S⊕ (~31,439 W/m²), TOI-813 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-813 is classified as a solar-type yellow star of spectral type G0 IV with an effective photospheric temperature of 5,907 K, a radius of 1.94 R☉, a mass of 1.32 M☉, an estimated bolometric luminosity of 4.111 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.73 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, TOI-813 shines at apparent V-band magnitude 10.358 (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-813 |
| Spectral Type | G0 IV |
| Effective Temp (Teff) | 5,907 K |
| Stellar Radius | 1.9400 R☉ |
| Stellar Mass | 1.3200 M☉ |
| Bolometric Luminosity | 4.111 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | 3.730 Gyr |
| Apparent Magnitude | V: 10.358 · G: 10.235 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.423000 AU |
| Orbital Period | 83.891 days |
| Mean Orbital Velocity | 54.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.6400° |
| Mean Bulk Density | 0.66 g/cm³ (26.1 km/s vesc) |
| Insolation Flux | 23.1000 S⊕ (~31,439 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 858.300 LY (263.145 pc) |