TOI-157 b
Astrophysical Synthesis & Habitability Characterization
TOI-157 b is a confirmed gas giant exoplanet orbiting the star TOI-157, located approximately 1160.1 light-years (355.68 parsecs) from the Solar System. First announced in 2020 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 1.2824% across the stellar disk), this world measures 14.415 Earth radii (1.29 Jupiter radii) and has a measured mass of 375.039 Earth masses (1.18 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.69 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.8 g⊕ (17.65 m/s²), and an escape velocity of 57.1 km/s.
In its orbital architecture around TOI-157, TOI-157 b completes one full revolution every 2.085 Earth days at a semi-major axis of 0.03138 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 163.8 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1588 K (+1315°C / +2399°F) and receiving 1,062.00 S⊕ (~1,445,382 W/m²), TOI-157 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-157 is classified as a solar-type yellow star of spectral type G9 IV with an effective photospheric temperature of 5,404 K, a radius of 1.167 R☉, a mass of 0.948 M☉, an estimated bolometric luminosity of 1.042 L☉. Stellar evolution modeling indicates an estimated stellar age of 12.82 Gyr and a metallicity of [Fe/H] = 0.24 dex (metal-rich relative to the Sun). From Earth, TOI-157 shines at apparent V-band magnitude 12.725 (faint and requiring research-grade or CCD telescopic photometry) 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-157 |
| Spectral Type | G9 IV |
| Effective Temp (Teff) | 5,404 K |
| Stellar Radius | 1.1670 R☉ |
| Stellar Mass | 0.9480 M☉ |
| Bolometric Luminosity | 1.042 L☉ |
| Metallicity [Fe/H] | 0.240 dex |
| Stellar Age | 12.820 Gyr |
| Apparent Magnitude | V: 12.725 · G: 12.514 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.031380 AU |
| Orbital Period | 2.085 days |
| Mean Orbital Velocity | 163.8 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 82.0100° |
| Mean Bulk Density | 0.69 g/cm³ (57.1 km/s vesc) |
| Insolation Flux | 1062.0000 S⊕ (~1,445,382 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1160.100 LY (355.683 pc) |