TOI-603 b
Astrophysical Synthesis & Habitability Characterization
TOI-603 b is a confirmed gas giant exoplanet orbiting the star TOI-603, located approximately 671.6 light-years (205.92 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 0.2093% across the stellar disk), this world measures 7.37 Earth radii (0.66 Jupiter radii) and has a measured mass of 33 Earth masses (0.1 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.45 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.61 g⊕ (5.98 m/s²), and an escape velocity of 23.7 km/s.
In its orbital architecture around TOI-603, TOI-603 b completes one full revolution every 16.18 Earth days at a semi-major axis of 0.1282 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 86.2 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 899 K (+626°C / +1159°F) and receiving 157.00 S⊕ (~213,677 W/m²), TOI-603 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-603 is classified as a warm F-type star of spectral type F8 IV with an effective photospheric temperature of 6,027 K, a radius of 1.477 R☉, a mass of 1.24 M☉, an estimated bolometric luminosity of 2.583 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.183 dex (metal-rich relative to the Sun). From Earth, TOI-603 shines at apparent V-band magnitude 10.312 (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-603 |
| Spectral Type | F8 IV |
| Effective Temp (Teff) | 6,027 K |
| Stellar Radius | 1.4770 R☉ |
| Stellar Mass | 1.2400 M☉ |
| Bolometric Luminosity | 2.583 L☉ |
| Metallicity [Fe/H] | 0.183 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 10.312 · G: 10.164 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.128200 AU |
| Orbital Period | 16.18 days |
| Mean Orbital Velocity | 86.2 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.5800° |
| Mean Bulk Density | 0.45 g/cm³ (23.7 km/s vesc) |
| Insolation Flux | 157.0000 S⊕ (~213,677 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 671.600 LY (205.924 pc) |