TOI-3688 A b
Astrophysical Synthesis & Habitability Characterization
TOI-3688 A b is a confirmed gas giant exoplanet orbiting the star TOI-3688 A, located approximately 1292.8 light-years (396.38 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 0.8484% across the stellar disk), this world measures 13.081 Earth radii (1.17 Jupiter radii) and has a measured mass of 311.472 Earth masses (0.98 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.77 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.82 g⊕ (17.85 m/s²), and an escape velocity of 54.6 km/s.
In its orbital architecture around TOI-3688 A, TOI-3688 A b completes one full revolution every 3.246 Earth days at a semi-major axis of 0.0456 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 152.8 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 1534 K (+1261°C / +2302°F) and receiving 924.30 S⊕ (~1,257,972 W/m²), TOI-3688 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-3688 A is classified as a stellar host with an effective photospheric temperature of 5,950 K, a radius of 1.302 R☉, a mass of 1.199 M☉, an estimated bolometric luminosity of 1.906 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.3 Gyr and a metallicity of [Fe/H] = 0.262 dex (metal-rich relative to the Sun). From Earth, TOI-3688 A shines at apparent V-band magnitude 12.241 (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-3688 A |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,950 K |
| Stellar Radius | 1.3020 R☉ |
| Stellar Mass | 1.1990 M☉ |
| Bolometric Luminosity | 1.906 L☉ |
| Metallicity [Fe/H] | 0.262 dex |
| Stellar Age | 3.300 Gyr |
| Apparent Magnitude | V: 12.241 · G: 12.369 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.045600 AU |
| Orbital Period | 3.246 days |
| Mean Orbital Velocity | 152.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 87.9000° |
| Mean Bulk Density | 0.77 g/cm³ (54.6 km/s vesc) |
| Insolation Flux | 924.3000 S⊕ (~1,257,972 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1292.800 LY (396.378 pc) |