TOI-5120 b
Astrophysical Synthesis & Habitability Characterization
TOI-5120 b is a confirmed gas giant exoplanet orbiting the star TOI-5120, located approximately 750 light-years (229.96 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 0.4918% across the stellar disk), this world measures 10.862 Earth radii (0.97 Jupiter radii) and has a measured mass of 390.929 Earth masses (1.23 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.68 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.31 g⊕ (32.46 m/s²), and an escape velocity of 67.1 km/s.
In its orbital architecture around TOI-5120, TOI-5120 b completes one full revolution every 24.916 Earth days at a semi-major axis of 0.172 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 75.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.1 carries the world between 0.1548 AU at periapsis and 0.1892 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 796 K (+523°C / +973°F) and receiving 66.00 S⊕ (~89,826 W/m²), TOI-5120 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5120 is classified as a stellar host with an effective photospheric temperature of 5,763 K, a radius of 1.42 R☉, a mass of 1.12 M☉, an estimated bolometric luminosity of 1.996 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.5 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, TOI-5120 shines at apparent V-band magnitude 10.792 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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-5120 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,763 K |
| Stellar Radius | 1.4200 R☉ |
| Stellar Mass | 1.1200 M☉ |
| Bolometric Luminosity | 1.996 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 7.500 Gyr |
| Apparent Magnitude | V: 10.792 · G: 10.665 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.172000 AU |
| Orbital Period | 24.916 days |
| Mean Orbital Velocity | 75.1 km/s |
| Orbital Eccentricity (e) | 0.10000 |
| Orbital Inclination (i) | 89.2000° |
| Mean Bulk Density | 1.68 g/cm³ (67.1 km/s vesc) |
| Insolation Flux | 66.0000 S⊕ (~89,826 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 750.000 LY (229.962 pc) |