TOI-1789 b
Astrophysical Synthesis & Habitability Characterization
TOI-1789 b is a confirmed gas giant exoplanet orbiting the star TOI-1789, located approximately 747.1 light-years (229.07 parsecs) from the Solar System. First announced in 2021 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.4659% across the stellar disk), this world measures 16.141 Earth radii (1.44 Jupiter radii) and has a measured mass of 222.48 Earth masses (0.7 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.29 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.85 g⊕ (8.34 m/s²), and an escape velocity of 41.5 km/s.
In its orbital architecture around TOI-1789, TOI-1789 b completes one full revolution every 3.209 Earth days at a semi-major axis of 0.04882 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 165.5 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1927 K (+1654°C / +3009°F) and receiving 2,300.00 S⊕ (~3,130,300 W/m²), TOI-1789 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1789 is classified as a warm F-type star of spectral type F with an effective photospheric temperature of 5,991 K, a radius of 2.168 R☉, a mass of 1.507 M☉, an estimated bolometric luminosity of 5.433 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.73 Gyr and a metallicity of [Fe/H] = 0.373 dex (metal-rich relative to the Sun). From Earth, TOI-1789 shines at apparent V-band magnitude 9.721 (accessible to binoculars and small amateur telescopes) 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-1789 |
| Spectral Type | F |
| Effective Temp (Teff) | 5,991 K |
| Stellar Radius | 2.1680 R☉ |
| Stellar Mass | 1.5070 M☉ |
| Bolometric Luminosity | 5.433 L☉ |
| Metallicity [Fe/H] | 0.373 dex |
| Stellar Age | 2.730 Gyr |
| Apparent Magnitude | V: 9.721 · G: 9.584 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.048820 AU |
| Orbital Period | 3.209 days |
| Mean Orbital Velocity | 165.5 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 78.4100° |
| Mean Bulk Density | 0.29 g/cm³ (41.5 km/s vesc) |
| Insolation Flux | 2300.0000 S⊕ (~3,130,300 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 747.100 LY (229.067 pc) |