TOI-904 c
Astrophysical Synthesis & Habitability Characterization
TOI-904 c is a confirmed sub-neptune exoplanet orbiting the star TOI-904, located approximately 150.3 light-years (46.09 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1421% across the stellar disk), this world measures 2.167 Earth radii and has a measured mass of 5.34 Earth masses. Combining its mass and radius yields a mean bulk density of 2.89 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 17.6 km/s.
In its orbital architecture around TOI-904, TOI-904 c completes one full revolution every 84 Earth days at a semi-major axis of 0.312 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 40.4 km/s (compared to Earth's 29.8 km/s).
✓ Classified as a Temperate Habitable Zone Candidate.
With an estimated equilibrium temperature of 217 K (-56°C / -69°F) and an incident stellar irradiance of 0.54 S⊕ (~742 W/m²), TOI-904 c orbits within the empirical circumstellar habitable zone where a rocky surface under sufficient atmospheric pressure can maintain liquid surface water.
The host star TOI-904 is classified as a stellar host with an effective photospheric temperature of 3,770 K, a radius of 0.527 R☉, a mass of 0.557 M☉, an estimated bolometric luminosity of 0.05 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.5 Gyr and a metallicity of [Fe/H] = 0.022 dex (near-solar heavy-element abundance). From Earth, TOI-904 shines at apparent V-band magnitude 12.588 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-904 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-904 c sharing its stellar neighborhood alongside TOI-904 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-904 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 3,770 K |
| Stellar Radius | 0.5270 R☉ |
| Stellar Mass | 0.5570 M☉ |
| Bolometric Luminosity | 0.05 L☉ |
| Metallicity [Fe/H] | 0.022 dex |
| Stellar Age | 1.500 Gyr |
| Apparent Magnitude | V: 12.588 · G: 11.856 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.312000 AU |
| Orbital Period | 84 days |
| Mean Orbital Velocity | 40.4 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.8300° |
| Mean Bulk Density | 2.89 g/cm³ (17.6 km/s vesc) |
| Insolation Flux | 0.5449 S⊕ (~742 W/m²) |
| Habitable Zone Status | ★ Temperate Zone |
| Celestial Distance | 150.300 LY (46.089 pc) |