TOI-4578 b
Astrophysical Synthesis & Habitability Characterization
TOI-4578 b is a confirmed sub-neptune exoplanet orbiting the star TOI-4578, located approximately 594.4 light-years (182.25 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 0.0561% across the stellar disk), this world measures 2.27 Earth radii and has a measured mass of 5.77 Earth masses. Combining its mass and radius yields a mean bulk density of 2.72 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.12 g⊕ (10.98 m/s²), and an escape velocity of 17.8 km/s.
In its orbital architecture around TOI-4578, TOI-4578 b completes one full revolution every 8.624 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 842 K (+569°C / +1056°F) and receiving 119.02 S⊕ (~161,993 W/m²), TOI-4578 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4578 is classified as a stellar host with an effective photospheric temperature of 5,951 K, a radius of 0.8787 R☉, a mass of 1.077 M☉, an estimated bolometric luminosity of 0.869 L☉. From Earth, TOI-4578 shines at apparent V-band magnitude 11.362 (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-4578 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,951 K |
| Stellar Radius | 0.8787 R☉ |
| Stellar Mass | 1.0770 M☉ |
| Bolometric Luminosity | 0.869 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 11.362 · G: 11.196 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 8.624 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.9414° |
| Mean Bulk Density | 2.72 g/cm³ (17.8 km/s vesc) |
| Insolation Flux | 119.0248 S⊕ (~161,993 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 594.400 LY (182.249 pc) |