TOI-6109 c
Astrophysical Synthesis & Habitability Characterization
TOI-6109 c is a confirmed sub-neptune exoplanet orbiting the star TOI-6109, located approximately 494.9 light-years (151.74 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 0.1883% across the stellar disk), this world measures 4.833 Earth radii (0.43 Jupiter radii) and has a measured mass of 20.8 Earth masses. Combining its mass and radius yields a mean bulk density of 1.02 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.89 g⊕ (8.73 m/s²), and an escape velocity of 23.2 km/s.
In its orbital architecture around TOI-6109, TOI-6109 c completes one full revolution every 8.539 Earth days at a semi-major axis of 0.0786 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 100.1 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 786 K (+513°C / +955°F) and receiving 63.39 S⊕ (~86,276 W/m²), TOI-6109 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-6109 is classified as a solar-type yellow star of spectral type G3 with an effective photospheric temperature of 5,660 K, a radius of 1.021 R☉, a mass of 1.03 M☉, an estimated bolometric luminosity of 0.96 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.075 Gyr and a metallicity of [Fe/H] = 0.09 dex (metal-rich relative to the Sun). From Earth, TOI-6109 shines at apparent V-band magnitude 11.05 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The TOI-6109 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-6109 c sharing its stellar neighborhood alongside TOI-6109 b.
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-6109 |
| Spectral Type | G3 |
| Effective Temp (Teff) | 5,660 K |
| Stellar Radius | 1.0210 R☉ |
| Stellar Mass | 1.0300 M☉ |
| Bolometric Luminosity | 0.96 L☉ |
| Metallicity [Fe/H] | 0.090 dex |
| Stellar Age | 0.075 Gyr |
| Apparent Magnitude | V: 11.050 · G: 10.832 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.078600 AU |
| Orbital Period | 8.539 days |
| Mean Orbital Velocity | 100.1 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 87.2000° |
| Mean Bulk Density | 1.02 g/cm³ (23.2 km/s vesc) |
| Insolation Flux | 63.3913 S⊕ (~86,276 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 494.900 LY (151.738 pc) |