TOI-3851 b
Astrophysical Synthesis & Habitability Characterization
TOI-3851 b is a confirmed sub-neptune exoplanet orbiting the star TOI-3851, located approximately 973.1 light-years (298.35 parsecs) from the Solar System. First announced in 2026 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1262% across the stellar disk), this world measures 4.76 Earth radii (0.42 Jupiter radii) and has a measured mass of 20.3 Earth masses. Combining its mass and radius yields a mean bulk density of 1.04 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.9 g⊕ (8.83 m/s²), and an escape velocity of 23.1 km/s.
In its orbital architecture around TOI-3851, TOI-3851 b completes one full revolution every 3.383 Earth days. 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 1355 K (+1082°C / +1980°F) and receiving 559.63 S⊕ (~761,650 W/m²), TOI-3851 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-3851 is classified as a stellar host with an effective photospheric temperature of 5,838 K, a radius of 1.2283 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 1.572 L☉. From Earth, TOI-3851 shines at apparent V-band magnitude 11.776 (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-3851 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,838 K |
| Stellar Radius | 1.2283 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 1.572 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 11.776 · G: 11.612 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 3.383 days |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.04 g/cm³ (23.1 km/s vesc) |
| Insolation Flux | 559.6250 S⊕ (~761,650 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 973.100 LY (298.349 pc) |