TOI-6303 b
Astrophysical Synthesis & Habitability Characterization
TOI-6303 b is a confirmed gas giant exoplanet orbiting the star TOI-6303, located approximately 496.5 light-years (152.22 parsecs) from the Solar System. First announced in 2025 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 3.0442% across the stellar disk), this world measures 11.59 Earth radii (1.03 Jupiter radii) and has a measured mass of 2493 Earth masses (7.84 Jupiter masses). Combining its mass and radius yields a mean bulk density of 8.83 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 18.56 g⊕ (182.01 m/s²), and an escape velocity of 164.1 km/s.
In its orbital architecture around TOI-6303, TOI-6303 b completes one full revolution every 9.485 Earth days at a semi-major axis of 0.0761 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 87.3 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.02 (ranging from 0.0746 AU at periapsis to 0.0776 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 541 K (+268°C / +514°F) and receiving 14.28 S⊕ (~19,435 W/m²), TOI-6303 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-6303 is classified as a stellar host with an effective photospheric temperature of 3,977 K, a radius of 0.609 R☉, a mass of 0.644 M☉, an estimated bolometric luminosity of 0.083 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.4 Gyr and a metallicity of [Fe/H] = 0.44 dex (metal-rich relative to the Sun). From Earth, TOI-6303 shines at apparent V-band magnitude 14.639 (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-6303 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,977 K |
| Stellar Radius | 0.6090 R☉ |
| Stellar Mass | 0.6440 M☉ |
| Bolometric Luminosity | 0.083 L☉ |
| Metallicity [Fe/H] | 0.440 dex |
| Stellar Age | 6.400 Gyr |
| Apparent Magnitude | V: 14.639 · G: 13.911 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.076100 AU |
| Orbital Period | 9.485 days |
| Mean Orbital Velocity | 87.3 km/s |
| Orbital Eccentricity (e) | 0.02000 |
| Orbital Inclination (i) | 89.0300° |
| Mean Bulk Density | 8.83 g/cm³ (164.1 km/s vesc) |
| Insolation Flux | 14.2800 S⊕ (~19,435 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 496.500 LY (152.219 pc) |