TOI-2158 b
Astrophysical Synthesis & Habitability Characterization
TOI-2158 b is a confirmed gas giant exoplanet orbiting the star TOI-2158, located approximately 647.3 light-years (198.47 parsecs) from the Solar System. First announced in 2022 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.4896% across the stellar disk), this world measures 10.761 Earth radii (0.96 Jupiter radii) and has a measured mass of 260.619 Earth masses (0.82 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.15 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.25 g⊕ (22.06 m/s²), and an escape velocity of 55 km/s.
In its orbital architecture around TOI-2158, TOI-2158 b completes one full revolution every 8.601 Earth days at a semi-major axis of 0.075 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 94.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.07 carries the world between 0.0697 AU at periapsis and 0.0803 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1188 K (+915°C / +1679°F) and receiving 81.50 S⊕ (~110,920 W/m²), TOI-2158 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-2158 is classified as a stellar host with an effective photospheric temperature of 5,673 K, a radius of 1.41 R☉, a mass of 1.12 M☉, an estimated bolometric luminosity of 1.847 L☉. Stellar evolution modeling indicates an estimated stellar age of 8 Gyr and a metallicity of [Fe/H] = 0.47 dex (metal-rich relative to the Sun). From Earth, TOI-2158 shines at apparent V-band magnitude 10.887 (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-2158 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,673 K |
| Stellar Radius | 1.4100 R☉ |
| Stellar Mass | 1.1200 M☉ |
| Bolometric Luminosity | 1.847 L☉ |
| Metallicity [Fe/H] | 0.470 dex |
| Stellar Age | 8.000 Gyr |
| Apparent Magnitude | V: 10.887 · G: 10.672 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.075000 AU |
| Orbital Period | 8.601 days |
| Mean Orbital Velocity | 94.9 km/s |
| Orbital Eccentricity (e) | 0.07000 |
| Orbital Inclination (i) | 85.7000° |
| Mean Bulk Density | 1.15 g/cm³ (55 km/s vesc) |
| Insolation Flux | 81.4989 S⊕ (~110,920 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 647.300 LY (198.473 pc) |