TOI-5573 b
Astrophysical Synthesis & Habitability Characterization
TOI-5573 b is a confirmed gas giant exoplanet orbiting the star TOI-5573, located approximately 608.5 light-years (186.56 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 2.2645% across the stellar disk), this world measures 9.75 Earth radii (0.87 Jupiter radii) and has a measured mass of 112 Earth masses (0.35 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.67 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.18 g⊕ (11.57 m/s²), and an escape velocity of 37.9 km/s.
In its orbital architecture around TOI-5573, TOI-5573 b completes one full revolution every 8.798 Earth days at a semi-major axis of 0.0712 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 88 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.072 carries the world between 0.0661 AU at periapsis and 0.0763 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 528 K (+255°C / +491°F) and receiving 12.92 S⊕ (~17,584 W/m²), TOI-5573 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-5573 is classified as a stellar host with an effective photospheric temperature of 3,790 K, a radius of 0.594 R☉, a mass of 0.619 M☉, an estimated bolometric luminosity of 0.065 L☉. Stellar evolution modeling indicates an estimated stellar age of 9.7 Gyr and a metallicity of [Fe/H] = 0.42 dex (metal-rich relative to the Sun). From Earth, TOI-5573 shines at apparent V-band magnitude 15.508 (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-5573 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,790 K |
| Stellar Radius | 0.5940 R☉ |
| Stellar Mass | 0.6190 M☉ |
| Bolometric Luminosity | 0.065 L☉ |
| Metallicity [Fe/H] | 0.420 dex |
| Stellar Age | 9.700 Gyr |
| Apparent Magnitude | V: 15.508 · G: 14.674 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.071200 AU |
| Orbital Period | 8.798 days |
| Mean Orbital Velocity | 88 km/s |
| Orbital Eccentricity (e) | 0.07200 |
| Orbital Inclination (i) | 89.0100° |
| Mean Bulk Density | 0.67 g/cm³ (37.9 km/s vesc) |
| Insolation Flux | 12.9200 S⊕ (~17,584 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 608.500 LY (186.562 pc) |