TOI-269 b
Astrophysical Synthesis & Habitability Characterization
TOI-269 b is a confirmed sub-neptune exoplanet orbiting the star TOI-269, located approximately 186 light-years (57.02 parsecs) from the Solar System. First announced in 2021 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.4071% across the stellar disk), this world measures 2.77 Earth radii and has a measured mass of 8.8 Earth masses. Combining its mass and radius yields a mean bulk density of 2.28 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.15 g⊕ (11.28 m/s²), and an escape velocity of 19.9 km/s.
In its orbital architecture around TOI-269, TOI-269 b completes one full revolution every 3.698 Earth days at a semi-major axis of 0.0345 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 101.5 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.425, swinging from 0.0198 AU at periapsis out to 0.0492 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 531 K (+258°C / +496°F) and receiving 19.00 S⊕ (~25,859 W/m²), TOI-269 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-269 is classified as a low-mass red dwarf of spectral type M2 V with an effective photospheric temperature of 3,514 K, a radius of 0.398 R☉, a mass of 0.3917 M☉, an estimated bolometric luminosity of 0.022 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.29 dex (metal-poor relative to the Sun). From Earth, TOI-269 shines at apparent V-band magnitude 14.37 (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-269 |
| Spectral Type | M2 V |
| Effective Temp (Teff) | 3,514 K |
| Stellar Radius | 0.3980 R☉ |
| Stellar Mass | 0.3917 M☉ |
| Bolometric Luminosity | 0.022 L☉ |
| Metallicity [Fe/H] | -0.290 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 14.370 · G: 13.426 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.034500 AU |
| Orbital Period | 3.698 days |
| Mean Orbital Velocity | 101.5 km/s |
| Orbital Eccentricity (e) | 0.42500 |
| Orbital Inclination (i) | 88.1400° |
| Mean Bulk Density | 2.28 g/cm³ (19.9 km/s vesc) |
| Insolation Flux | 19.0000 S⊕ (~25,859 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 186.000 LY (57.023 pc) |