TOI-5126 b
Astrophysical Synthesis & Habitability Characterization
TOI-5126 b is a confirmed sub-neptune exoplanet orbiting the star TOI-5126, located approximately 523.2 light-years (160.41 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 0.1226% across the stellar disk), this world measures 4.74 Earth radii (0.42 Jupiter radii) and has a measured mass of 20.2 Earth masses. Combining its mass and radius yields a mean bulk density of 1.05 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 23.1 km/s.
In its orbital architecture around TOI-5126, TOI-5126 b completes one full revolution every 5.459 Earth days at a semi-major axis of 0.06519 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 129.9 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1442 K (+1169°C / +2136°F) and receiving 467.00 S⊕ (~635,587 W/m²), TOI-5126 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5126 is classified as a warm F-type star of spectral type F V with an effective photospheric temperature of 6,150 K, a radius of 1.241 R☉, a mass of 1.24 M☉, an estimated bolometric luminosity of 1.977 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.8 Gyr and a metallicity of [Fe/H] = 0.18 dex (metal-rich relative to the Sun). From Earth, TOI-5126 shines at apparent V-band magnitude 10.141 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The TOI-5126 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-5126 b sharing its stellar neighborhood alongside TOI-5126 c.
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-5126 |
| Spectral Type | F V |
| Effective Temp (Teff) | 6,150 K |
| Stellar Radius | 1.2410 R☉ |
| Stellar Mass | 1.2400 M☉ |
| Bolometric Luminosity | 1.977 L☉ |
| Metallicity [Fe/H] | 0.180 dex |
| Stellar Age | 0.800 Gyr |
| Apparent Magnitude | V: 10.141 · G: 9.936 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.065190 AU |
| Orbital Period | 5.459 days |
| Mean Orbital Velocity | 129.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.7900° |
| Mean Bulk Density | 1.05 g/cm³ (23.1 km/s vesc) |
| Insolation Flux | 467.0000 S⊕ (~635,587 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 523.200 LY (160.414 pc) |