TOI-1338 c
Astrophysical Synthesis & Habitability Characterization
TOI-1338 c is a confirmed gas giant exoplanet orbiting the star TOI-1338 A, located approximately 1301.4 light-years (399.02 parsecs) from the Solar System. First announced in 2023 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 10.3 Earth radii (0.92 Jupiter radii) and has a measured mass of 75.4 Earth masses (0.24 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.38 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.71 g⊕ (6.96 m/s²), and an escape velocity of 30.3 km/s.
In its orbital architecture around TOI-1338 A, TOI-1338 c completes one full revolution every 215.79 Earth days at a semi-major axis of 0.794 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 40 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.037 (ranging from 0.7646 AU at periapsis to 0.8234 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 355 K (+82°C / +180°F) and receiving 3.38 S⊕ (~4,605 W/m²), TOI-1338 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1338 A is classified as a warm F-type star of spectral type F8 with an effective photospheric temperature of 5,723 K, a radius of 1.313 R☉, a mass of 1.0936 M☉, an estimated bolometric luminosity of 1.659 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.4 Gyr and a metallicity of [Fe/H] = 0.01 dex (near-solar heavy-element abundance). From Earth, TOI-1338 A shines at apparent V-band magnitude 11.722 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-1338 A system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-1338 c sharing its stellar neighborhood alongside TOI-1338 b.
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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | TOI-1338 A |
| Spectral Type | F8 |
| Effective Temp (Teff) | 5,723 K |
| Stellar Radius | 1.3130 R☉ |
| Stellar Mass | 1.0936 M☉ |
| Bolometric Luminosity | 1.659 L☉ |
| Metallicity [Fe/H] | 0.010 dex |
| Stellar Age | 4.400 Gyr |
| Apparent Magnitude | V: 11.722 · G: 11.876 |
| System Architecture | 2 Stars, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.794000 AU |
| Orbital Period | 215.79 days |
| Mean Orbital Velocity | 40 km/s |
| Orbital Eccentricity (e) | 0.03700 |
| Orbital Inclination (i) | 97.0000° |
| Mean Bulk Density | 0.38 g/cm³ (30.3 km/s vesc) |
| Insolation Flux | 3.3833 S⊕ (~4,605 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1301.400 LY (399.017 pc) |