TOI-7166 b
Astrophysical Synthesis & Habitability Characterization
TOI-7166 b is a confirmed sub-neptune exoplanet orbiting the star TOI-7166, located approximately 115.5 light-years (35.42 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 0.689% across the stellar disk), this world measures 2.01 Earth radii and has a measured mass of 4.7 Earth masses. Combining its mass and radius yields a mean bulk density of 3.19 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 17.1 km/s.
In its orbital architecture around TOI-7166, TOI-7166 b completes one full revolution every 12.921 Earth days at a semi-major axis of 0.06191 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 52.1 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.
✓ Classified as a Temperate Habitable Zone Candidate.
With an estimated equilibrium temperature of 249 K (-24°C / -11°F) and an incident stellar irradiance of 1.07 S⊕ (~1,456 W/m²), TOI-7166 b orbits within the empirical circumstellar habitable zone where a rocky surface under sufficient atmospheric pressure can maintain liquid surface water.
The host star TOI-7166 is classified as a low-mass red dwarf of spectral type M4.5+/-0.5 with an effective photospheric temperature of 3,099 K, a radius of 0.222 R☉, a mass of 0.19 M☉, an estimated bolometric luminosity of 0.00408 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 Gyr and a metallicity of [Fe/H] = -0.2 dex (metal-poor relative to the Sun). From Earth, TOI-7166 shines at apparent V-band magnitude 15.79 (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-7166 |
| Spectral Type | M4.5+/-0.5 |
| Effective Temp (Teff) | 3,099 K |
| Stellar Radius | 0.2220 R☉ |
| Stellar Mass | 0.1900 M☉ |
| Bolometric Luminosity | 0.00408 L☉ |
| Metallicity [Fe/H] | -0.200 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 15.790 · G: 14.492 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.061910 AU |
| Orbital Period | 12.921 days |
| Mean Orbital Velocity | 52.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.8000° |
| Mean Bulk Density | 3.19 g/cm³ (17.1 km/s vesc) |
| Insolation Flux | 1.0700 S⊕ (~1,456 W/m²) |
| Habitable Zone Status | ★ Temperate Zone |
| Celestial Distance | 115.500 LY (35.415 pc) |