TOI-4308 b
Astrophysical Synthesis & Habitability Characterization
TOI-4308 b is a confirmed sub-neptune exoplanet orbiting the star TOI-4308, located approximately 355.3 light-years (108.93 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 0.0781% across the stellar disk), this world measures 2.419 Earth radii and has a measured mass of 6.43 Earth masses. Combining its mass and radius yields a mean bulk density of 2.5 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.2 km/s.
In its orbital architecture around TOI-4308, TOI-4308 b completes one full revolution every 9.151 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 763 K (+490°C / +914°F) and receiving 55.36 S⊕ (~75,347 W/m²), TOI-4308 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4308 is classified as a stellar host with an effective photospheric temperature of 5,243 K, a radius of 0.7934 R☉, a mass of 0.9 M☉, an estimated bolometric luminosity of 0.427 L☉. From Earth, TOI-4308 shines at apparent V-band magnitude 11.251 (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-4308 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,243 K |
| Stellar Radius | 0.7934 R☉ |
| Stellar Mass | 0.9000 M☉ |
| Bolometric Luminosity | 0.427 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 11.251 · G: 10.865 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 9.151 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.0700° |
| Mean Bulk Density | 2.5 g/cm³ (18.2 km/s vesc) |
| Insolation Flux | 55.3616 S⊕ (~75,347 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 355.300 LY (108.932 pc) |