TOI-4311 c
Astrophysical Synthesis & Habitability Characterization
TOI-4311 c is a confirmed sub-neptune exoplanet orbiting the star TOI-4311, located approximately 440.3 light-years (134.99 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 0.072% across the stellar disk), this world measures 2.47 Earth radii and has a measured mass of 13.58 Earth masses. Combining its mass and radius yields a mean bulk density of 4.97 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 2.23 g⊕ (21.87 m/s²), and an escape velocity of 26.2 km/s.
In its orbital architecture around TOI-4311, TOI-4311 c completes one full revolution every 15.07 Earth days at a semi-major axis of 0.1116 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 80.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.22 carries the world between 0.087 AU at periapsis and 0.1362 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 671 K (+398°C / +748°F) and receiving 33.80 S⊕ (~46,002 W/m²), TOI-4311 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4311 is classified as an orange K-type star of spectral type K with an effective photospheric temperature of 5,063 K, a radius of 0.8441 R☉, a mass of 0.816 M☉, an estimated bolometric luminosity of 0.42 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.6 Gyr and a metallicity of [Fe/H] = -0.065 dex (near-solar heavy-element abundance). From Earth, TOI-4311 shines at apparent V-band magnitude 11.388 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-4311 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-4311 c sharing its stellar neighborhood alongside TOI-4311 b.
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-4311 |
| Spectral Type | K |
| Effective Temp (Teff) | 5,063 K |
| Stellar Radius | 0.8441 R☉ |
| Stellar Mass | 0.8160 M☉ |
| Bolometric Luminosity | 0.42 L☉ |
| Metallicity [Fe/H] | -0.065 dex |
| Stellar Age | 6.600 Gyr |
| Apparent Magnitude | V: 11.388 · G: 11.265 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.111600 AU |
| Orbital Period | 15.07 days |
| Mean Orbital Velocity | 80.6 km/s |
| Orbital Eccentricity (e) | 0.22000 |
| Orbital Inclination (i) | 89.0500° |
| Mean Bulk Density | 4.97 g/cm³ (26.2 km/s vesc) |
| Insolation Flux | 33.8000 S⊕ (~46,002 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 440.300 LY (134.988 pc) |