TOI-904 b
Astrophysical Synthesis & Habitability Characterization
TOI-904 b 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 0.1781% across the stellar disk), this world measures 2.426 Earth radii and has a measured mass of 6.46 Earth masses. Combining its mass and radius yields a mean bulk density of 2.49 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.3 km/s.
In its orbital architecture around TOI-904, TOI-904 b completes one full revolution every 10.877 Earth days at a semi-major axis of 0.056 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 56 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 429 K (+156°C / +313°F) and receiving 8.32 S⊕ (~11,319 W/m²), TOI-904 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
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 b sharing its stellar neighborhood alongside TOI-904 c.
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) | 0.056000 AU |
| Orbital Period | 10.877 days |
| Mean Orbital Velocity | 56 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.1900° |
| Mean Bulk Density | 2.49 g/cm³ (18.3 km/s vesc) |
| Insolation Flux | 8.3169 S⊕ (~11,319 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 150.300 LY (46.089 pc) |