TOI-6699 b
Astrophysical Synthesis & Habitability Characterization
TOI-6699 b is a confirmed sub-neptune exoplanet orbiting the star TOI-6699, located approximately 280 light-years (85.85 parsecs) from the Solar System. First announced in 2026 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0802% across the stellar disk), this world measures 2.326 Earth radii and has a measured mass of 6.02 Earth masses. Combining its mass and radius yields a mean bulk density of 2.64 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.11 g⊕ (10.89 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around TOI-6699, TOI-6699 b completes one full revolution every 5.32 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 976 K (+703°C / +1297°F) and receiving 150.91 S⊕ (~205,389 W/m²), TOI-6699 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-6699 is classified as a stellar host with an effective photospheric temperature of 4,705 K, a radius of 0.7531 R☉, a mass of 0.75 M☉, an estimated bolometric luminosity of 0.249 L☉. From Earth, TOI-6699 shines at apparent V-band magnitude 11.51 (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-6699 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,705 K |
| Stellar Radius | 0.7531 R☉ |
| Stellar Mass | 0.7500 M☉ |
| Bolometric Luminosity | 0.249 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 11.510 · G: 11.030 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 5.32 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 87.9666° |
| Mean Bulk Density | 2.64 g/cm³ (18 km/s vesc) |
| Insolation Flux | 150.9100 S⊕ (~205,389 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 280.000 LY (85.846 pc) |