TOI-1117 b
Astrophysical Synthesis & Habitability Characterization
TOI-1117 b is a confirmed sub-neptune exoplanet orbiting the star TOI-1117, located approximately 546.6 light-years (167.6 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 0.0461% across the stellar disk), this world measures 2.46 Earth radii and has a measured mass of 8.9 Earth masses. Combining its mass and radius yields a mean bulk density of 3.3 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.47 g⊕ (14.42 m/s²), and an escape velocity of 21.3 km/s.
In its orbital architecture around TOI-1117, TOI-1117 b completes one full revolution every 2.228 Earth days at a semi-major axis of 0.033 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 161.1 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 1538 K (+1265°C / +2309°F) and receiving 928.00 S⊕ (~1,263,008 W/m²), TOI-1117 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1117 is classified as a solar-type yellow star of spectral type G5 V with an effective photospheric temperature of 5,635 K, a radius of 1.05 R☉, a mass of 0.97 M☉, an estimated bolometric luminosity of 0.997 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.42 Gyr and a metallicity of [Fe/H] = 0.136 dex (metal-rich relative to the Sun). From Earth, TOI-1117 shines at apparent V-band magnitude 11.016 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-1117 system is a multi-planet architecture hosting 3 confirmed worlds, with TOI-1117 b sharing its stellar neighborhood alongside TOI-1117 c, TOI-1117 d.
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-1117 |
| Spectral Type | G5 V |
| Effective Temp (Teff) | 5,635 K |
| Stellar Radius | 1.0500 R☉ |
| Stellar Mass | 0.9700 M☉ |
| Bolometric Luminosity | 0.997 L☉ |
| Metallicity [Fe/H] | 0.136 dex |
| Stellar Age | 4.420 Gyr |
| Apparent Magnitude | V: 11.016 · G: 10.862 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.033000 AU |
| Orbital Period | 2.228 days |
| Mean Orbital Velocity | 161.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.2000° |
| Mean Bulk Density | 3.3 g/cm³ (21.3 km/s vesc) |
| Insolation Flux | 928.0000 S⊕ (~1,263,008 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 546.600 LY (167.598 pc) |