TOI-5386 A b
Astrophysical Synthesis & Habitability Characterization
TOI-5386 A b is a confirmed gas giant exoplanet orbiting the star TOI-5386 A, located approximately 1286.6 light-years (394.49 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 1.1727% across the stellar disk), this world measures 14.706 Earth radii (1.31 Jupiter radii) and has a measured mass of 155.1 Earth masses (0.49 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.27 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.72 g⊕ (7.06 m/s²), and an escape velocity of 36.3 km/s.
In its orbital architecture around TOI-5386 A, TOI-5386 A b completes one full revolution every 3.622 Earth days at a semi-major axis of 0.04856 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 145.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.072 carries the world between 0.0451 AU at periapsis and 0.0521 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1488 K (+1215°C / +2219°F) and receiving 817.00 S⊕ (~1,111,937 W/m²), TOI-5386 A b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5386 A is classified as a stellar host with an effective photospheric temperature of 6,094 K, a radius of 1.245 R☉, a mass of 1.165 M☉, an estimated bolometric luminosity of 1.918 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.4 Gyr and a metallicity of [Fe/H] = 0.182 dex (metal-rich relative to the Sun). From Earth, TOI-5386 A shines at apparent V-band magnitude 11.554 (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-5386 A |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 6,094 K |
| Stellar Radius | 1.2450 R☉ |
| Stellar Mass | 1.1650 M☉ |
| Bolometric Luminosity | 1.918 L☉ |
| Metallicity [Fe/H] | 0.182 dex |
| Stellar Age | 3.400 Gyr |
| Apparent Magnitude | V: 11.554 · G: 11.760 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048560 AU |
| Orbital Period | 3.622 days |
| Mean Orbital Velocity | 145.9 km/s |
| Orbital Eccentricity (e) | 0.07200 |
| Orbital Inclination (i) | 83.9510° |
| Mean Bulk Density | 0.27 g/cm³ (36.3 km/s vesc) |
| Insolation Flux | 817.0000 S⊕ (~1,111,937 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1286.600 LY (394.486 pc) |