TOI-4851 b
Astrophysical Synthesis & Habitability Characterization
TOI-4851 b is a confirmed sub-neptune exoplanet orbiting the star TOI-4851, located approximately 410.2 light-years (125.77 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 0.0489% across the stellar disk), this world measures 2.77 Earth radii and has a measured mass of 8.1 Earth masses. Combining its mass and radius yields a mean bulk density of 2.1 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 19.1 km/s.
In its orbital architecture around TOI-4851, TOI-4851 b completes one full revolution every 21.609 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 888 K (+615°C / +1139°F) and receiving 103.51 S⊕ (~140,874 W/m²), TOI-4851 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4851 is classified as a stellar host with an effective photospheric temperature of 5,967 K, a radius of 1.1479 R☉, a mass of 1.09 M☉, an estimated bolometric luminosity of 1.499 L☉. From Earth, TOI-4851 shines at apparent V-band magnitude 10.135 (faint and requiring research-grade or CCD telescopic photometry) in the Southern 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-4851 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,967 K |
| Stellar Radius | 1.1479 R☉ |
| Stellar Mass | 1.0900 M☉ |
| Bolometric Luminosity | 1.499 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 10.135 · G: 9.833 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 21.609 days |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.1 g/cm³ (19.1 km/s vesc) |
| Insolation Flux | 103.5080 S⊕ (~140,874 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 410.200 LY (125.772 pc) |