TOI-1408 b
Astrophysical Synthesis & Habitability Characterization
TOI-1408 b is a confirmed gas giant exoplanet orbiting the star TOI-1408, located approximately 454.9 light-years (139.48 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 2.2441% across the stellar disk), this world measures 25 Earth radii (2.23 Jupiter radii) and has a measured mass of 593 Earth masses (1.87 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.21 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.95 g⊕ (9.32 m/s²), and an escape velocity of 54.5 km/s.
In its orbital architecture around TOI-1408, TOI-1408 b completes one full revolution every 4.426 Earth days at a semi-major axis of 0.05778 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 142 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.0023 (ranging from 0.0576 AU at periapsis to 0.0579 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1293 K (+1020°C / +1868°F) and receiving 465.18 S⊕ (~633,109 W/m²), TOI-1408 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1408 is classified as a warm F-type star of spectral type F8 V with an effective photospheric temperature of 6,117 K, a radius of 1.53 R☉, a mass of 1.312 M☉, an estimated bolometric luminosity of 2.941 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.7 Gyr and a metallicity of [Fe/H] = 0.25 dex (metal-rich relative to the Sun). From Earth, TOI-1408 shines at apparent V-band magnitude 9.27 (accessible to binoculars and small amateur telescopes) in the Northern celestial hemisphere. The TOI-1408 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-1408 b sharing its stellar neighborhood alongside TOI-1408 c.
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-1408 |
| Spectral Type | F8 V |
| Effective Temp (Teff) | 6,117 K |
| Stellar Radius | 1.5300 R☉ |
| Stellar Mass | 1.3120 M☉ |
| Bolometric Luminosity | 2.941 L☉ |
| Metallicity [Fe/H] | 0.250 dex |
| Stellar Age | 2.700 Gyr |
| Apparent Magnitude | V: 9.270 · G: 9.188 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.057780 AU |
| Orbital Period | 4.426 days |
| Mean Orbital Velocity | 142 km/s |
| Orbital Eccentricity (e) | 0.00230 |
| Orbital Inclination (i) | 82.4000° |
| Mean Bulk Density | 0.21 g/cm³ (54.5 km/s vesc) |
| Insolation Flux | 465.1790 S⊕ (~633,109 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 454.900 LY (139.484 pc) |