TOI-4551 b
Astrophysical Synthesis & Habitability Characterization
TOI-4551 b is a confirmed gas giant exoplanet orbiting the star TOI-4551, located approximately 704.5 light-years (215.99 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 0.0938% across the stellar disk), this world measures 11.859 Earth radii (1.06 Jupiter radii) and has a measured mass of 473.564 Earth masses (1.49 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.57 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 3.37 g⊕ (33.05 m/s²), and an escape velocity of 70.7 km/s.
In its orbital architecture around TOI-4551, TOI-4551 b completes one full revolution every 9.956 Earth days at a semi-major axis of 0.0994 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 108.6 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.101 carries the world between 0.0894 AU at periapsis and 0.1094 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1655 K (+1382°C / +2520°F) and receiving 1,247.74 S⊕ (~1,698,174 W/m²), TOI-4551 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4551 is classified as a stellar host with an effective photospheric temperature of 4,896 K, a radius of 3.55 R☉, a mass of 1.31 M☉, an estimated bolometric luminosity of 6.497 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.92 Gyr and a metallicity of [Fe/H] = 0.23 dex (metal-rich relative to the Sun). From Earth, TOI-4551 shines at apparent V-band magnitude 9.973 (accessible to binoculars and small amateur telescopes) in the Southern 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-4551 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,896 K |
| Stellar Radius | 3.5500 R☉ |
| Stellar Mass | 1.3100 M☉ |
| Bolometric Luminosity | 6.497 L☉ |
| Metallicity [Fe/H] | 0.230 dex |
| Stellar Age | 4.920 Gyr |
| Apparent Magnitude | V: 9.973 · G: 9.641 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.099400 AU |
| Orbital Period | 9.956 days |
| Mean Orbital Velocity | 108.6 km/s |
| Orbital Eccentricity (e) | 0.10100 |
| Orbital Inclination (i) | 86.9000° |
| Mean Bulk Density | 1.57 g/cm³ (70.7 km/s vesc) |
| Insolation Flux | 1247.7400 S⊕ (~1,698,174 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 704.500 LY (215.986 pc) |