TOI-4405 b
Astrophysical Synthesis & Habitability Characterization
TOI-4405 b is a confirmed sub-neptune exoplanet orbiting the star TOI-4405, located approximately 507.2 light-years (155.5 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 0.1163% across the stellar disk), this world measures 2.555 Earth radii and has a measured mass of 7.06 Earth masses. Combining its mass and radius yields a mean bulk density of 2.33 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18.6 km/s.
In its orbital architecture around TOI-4405, TOI-4405 b completes one full revolution every 5.921 Earth days.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 672 K (+399°C / +750°F) and receiving 48.16 S⊕ (~65,540 W/m²), TOI-4405 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4405 is classified as a stellar host with an effective photospheric temperature of 4,467 K, a radius of 0.687 R☉, a mass of 0.68 M☉, an estimated bolometric luminosity of 0.169 L☉. From Earth, TOI-4405 shines at apparent V-band magnitude 13.476 (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-4405 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,467 K |
| Stellar Radius | 0.6870 R☉ |
| Stellar Mass | 0.6800 M☉ |
| Bolometric Luminosity | 0.169 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 13.476 · G: 13.140 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 5.921 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 88.6991° |
| Mean Bulk Density | 2.33 g/cm³ (18.6 km/s vesc) |
| Insolation Flux | 48.1559 S⊕ (~65,540 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 507.200 LY (155.501 pc) |