TOI-426 b
Astrophysical Synthesis & Habitability Characterization
TOI-426 b is a confirmed sub-neptune exoplanet orbiting the star TOI-426, located approximately 370.5 light-years (113.59 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 0.0411% across the stellar disk), this world measures 2.19 Earth radii and has a measured mass of 6.7 Earth masses. Combining its mass and radius yields a mean bulk density of 3.52 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.4 g⊕ (13.73 m/s²), and an escape velocity of 19.6 km/s.
In its orbital architecture around TOI-426, TOI-426 b completes one full revolution every 1.321 Earth days at a semi-major axis of 0.02374 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 195.6 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1790 K (+1517°C / +2763°F) and receiving 1,711.00 S⊕ (~2,328,671 W/m²), TOI-426 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-426 is classified as a solar-type yellow star of spectral type G2 V with an effective photospheric temperature of 5,750 K, a radius of 0.99 R☉, a mass of 1 M☉, an estimated bolometric luminosity of 0.961 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.57 Gyr and a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, TOI-426 shines at apparent V-band magnitude 10.116 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-426 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-426 b sharing its stellar neighborhood alongside TOI-426 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-426 |
| Spectral Type | G2 V |
| Effective Temp (Teff) | 5,750 K |
| Stellar Radius | 0.9900 R☉ |
| Stellar Mass | 1.0000 M☉ |
| Bolometric Luminosity | 0.961 L☉ |
| Metallicity [Fe/H] | 0.160 dex |
| Stellar Age | 1.570 Gyr |
| Apparent Magnitude | V: 10.116 · G: 10.041 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.023740 AU |
| Orbital Period | 1.321 days |
| Mean Orbital Velocity | 195.6 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 87.0000° |
| Mean Bulk Density | 3.52 g/cm³ (19.6 km/s vesc) |
| Insolation Flux | 1711.0000 S⊕ (~2,328,671 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 370.500 LY (113.590 pc) |