TOI-426 c
Astrophysical Synthesis & Habitability Characterization
TOI-426 c is a confirmed gas giant exoplanet orbiting the star TOI-426, located approximately 370.5 light-years (113.59 parsecs) from the Solar System. First announced in 2026 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.6 Earth radii (1.21 Jupiter radii) and has a measured mass of 444 Earth masses (1.4 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.97 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.4 g⊕ (23.54 m/s²), and an escape velocity of 63.9 km/s.
In its orbital architecture around TOI-426, TOI-426 c completes one full revolution every 235.8 Earth days at a semi-major axis of 0.747 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 34.5 km/s (compared to Earth's 29.8 km/s).
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.600 R⊕, TOI-426 c exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
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 c sharing its stellar neighborhood alongside TOI-426 b.
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: La Silla Observatory · 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) | 0.747000 AU |
| Orbital Period | 235.8 days |
| Mean Orbital Velocity | 34.5 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.97 g/cm³ (63.9 km/s vesc) |
| Insolation Flux | 1.7300 S⊕ (~2,355 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 370.500 LY (113.590 pc) |