TOI-329 b
Astrophysical Synthesis & Habitability Characterization
TOI-329 b is a confirmed sub-neptune exoplanet orbiting the star TOI-329, located approximately 927.5 light-years (284.39 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0874% across the stellar disk), this world measures 4.941 Earth radii (0.44 Jupiter radii) and has a measured mass of 40.4 Earth masses (0.13 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.85 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.65 g⊕ (16.18 m/s²), and an escape velocity of 32 km/s.
In its orbital architecture around TOI-329, TOI-329 b completes one full revolution every 5.704 Earth days at a semi-major axis of 0.0638 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 121.7 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.39, swinging from 0.0389 AU at periapsis out to 0.0887 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1213 K (+940°C / +1724°F) and receiving 576.87 S⊕ (~785,127 W/m²), TOI-329 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-329 is classified as a stellar host with an effective photospheric temperature of 5,614 K, a radius of 1.5326 R☉, a mass of 1.0678 M☉, an estimated bolometric luminosity of 2.093 L☉. Stellar evolution modeling indicates an estimated stellar age of 8.7 Gyr and a metallicity of [Fe/H] = 0.205 dex (metal-rich relative to the Sun). From Earth, TOI-329 shines at apparent V-band magnitude 11.262 (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-329 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,614 K |
| Stellar Radius | 1.5326 R☉ |
| Stellar Mass | 1.0678 M☉ |
| Bolometric Luminosity | 2.093 L☉ |
| Metallicity [Fe/H] | 0.205 dex |
| Stellar Age | 8.700 Gyr |
| Apparent Magnitude | V: 11.262 · G: 11.154 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.063800 AU |
| Orbital Period | 5.704 days |
| Mean Orbital Velocity | 121.7 km/s |
| Orbital Eccentricity (e) | 0.39000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.85 g/cm³ (32 km/s vesc) |
| Insolation Flux | 576.8749 S⊕ (~785,127 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 927.500 LY (284.388 pc) |