TOI-5811 B b
Astrophysical Synthesis & Habitability Characterization
TOI-5811 B b is a confirmed gas giant exoplanet orbiting the star TOI-5811 B, located approximately 554.9 light-years (170.14 parsecs) from the Solar System. First announced in 2026 by Multiple Observatories using the Transit detection technique (producing an estimated primary transit depth of 0.2916% across the stellar disk), this world measures 21.97 Earth radii (1.96 Jupiter radii) and has a measured mass of 257.441 Earth masses (0.81 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.13 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.53 g⊕ (5.2 m/s²), and an escape velocity of 38.3 km/s.
In its orbital architecture around TOI-5811 B, TOI-5811 B b completes one full revolution every 6.257 Earth days at a semi-major axis of 0.0731 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 127.1 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1530 K (+1257°C / +2295°F) and receiving 1,320.00 S⊕ (~1,796,520 W/m²), TOI-5811 B b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5811 B is classified as an orange K-type star of spectral type K2 IV+ with an effective photospheric temperature of 4,840 K, a radius of 3.73 R☉, a mass of 1.08 M☉, an estimated bolometric luminosity of 6.85 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.06 dex (near-solar heavy-element abundance). From Earth, TOI-5811 B shines at apparent V-band magnitude 8.85 (accessible to binoculars and small amateur telescopes) 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-5811 B |
| Spectral Type | K2 IV+ |
| Effective Temp (Teff) | 4,840 K |
| Stellar Radius | 3.7300 R☉ |
| Stellar Mass | 1.0800 M☉ |
| Bolometric Luminosity | 6.85 L☉ |
| Metallicity [Fe/H] | -0.060 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 8.850 · G: 8.871 |
| System Architecture | 3 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.073100 AU |
| Orbital Period | 6.257 days |
| Mean Orbital Velocity | 127.1 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 76.7200° |
| Mean Bulk Density | 0.13 g/cm³ (38.3 km/s vesc) |
| Insolation Flux | 1320.0000 S⊕ (~1,796,520 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 554.900 LY (170.135 pc) |