TOI-5217 A b
Astrophysical Synthesis & Habitability Characterization
TOI-5217 A b is a confirmed gas giant exoplanet orbiting the star TOI-5217, located approximately 1687.9 light-years (517.51 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 0.3914% across the stellar disk), this world measures 15.524 Earth radii (1.38 Jupiter radii) and has a measured mass of 407.456 Earth masses (1.28 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.6 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.69 g⊕ (16.57 m/s²), and an escape velocity of 57.3 km/s.
In its orbital architecture around TOI-5217, TOI-5217 A b completes one full revolution every 4.371 Earth days at a semi-major axis of 0.0604 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 150.3 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 1817 K (+1544°C / +2811°F) and receiving 847.15 S⊕ (~1,152,966 W/m²), TOI-5217 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5217 is classified as a stellar host with an effective photospheric temperature of 6,140 K, a radius of 2.275 R☉, a mass of 1.537 M☉, an estimated bolometric luminosity of 6.6 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.299 dex (metal-rich relative to the Sun). From Earth, TOI-5217 shines at apparent V-band magnitude 11.58 (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-5217 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,140 K |
| Stellar Radius | 2.2750 R☉ |
| Stellar Mass | 1.5370 M☉ |
| Bolometric Luminosity | 6.6 L☉ |
| Metallicity [Fe/H] | 0.299 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 11.580 · G: 11.437 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.060400 AU |
| Orbital Period | 4.371 days |
| Mean Orbital Velocity | 150.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 82.9800° |
| Mean Bulk Density | 0.6 g/cm³ (57.3 km/s vesc) |
| Insolation Flux | 847.1460 S⊕ (~1,152,966 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1687.900 LY (517.506 pc) |