TOI-1811 b
Astrophysical Synthesis & Habitability Characterization
TOI-1811 b is a confirmed gas giant exoplanet orbiting the star TOI-1811, located approximately 418.2 light-years (128.23 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 1.7645% across the stellar disk), this world measures 11.142 Earth radii (0.99 Jupiter radii) and has a measured mass of 308.929 Earth masses (0.97 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.23 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.49 g⊕ (24.42 m/s²), and an escape velocity of 58.9 km/s.
In its orbital architecture around TOI-1811, TOI-1811 b completes one full revolution every 3.713 Earth days at a semi-major axis of 0.04389 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 128.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.052 carries the world between 0.0416 AU at periapsis and 0.0462 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 962 K (+689°C / +1272°F) and receiving 55.97 S⊕ (~76,181 W/m²), TOI-1811 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1811 is classified as a stellar host with an effective photospheric temperature of 4,766 K, a radius of 0.769 R☉, a mass of 0.817 M☉, an estimated bolometric luminosity of 0.274 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.9 Gyr and a metallicity of [Fe/H] = 0.306 dex (metal-rich relative to the Sun). From Earth, TOI-1811 shines at apparent V-band magnitude 11.966 (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-1811 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,766 K |
| Stellar Radius | 0.7690 R☉ |
| Stellar Mass | 0.8170 M☉ |
| Bolometric Luminosity | 0.274 L☉ |
| Metallicity [Fe/H] | 0.306 dex |
| Stellar Age | 5.900 Gyr |
| Apparent Magnitude | V: 11.966 · G: 11.757 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.043890 AU |
| Orbital Period | 3.713 days |
| Mean Orbital Velocity | 128.6 km/s |
| Orbital Eccentricity (e) | 0.05200 |
| Orbital Inclination (i) | 86.4800° |
| Mean Bulk Density | 1.23 g/cm³ (58.9 km/s vesc) |
| Insolation Flux | 55.9743 S⊕ (~76,181 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 418.200 LY (128.230 pc) |