TOI-4364 b
Astrophysical Synthesis & Habitability Characterization
TOI-4364 b is a confirmed sub-neptune exoplanet orbiting the star TOI-4364, located approximately 143.4 light-years (43.97 parsecs) from the Solar System. First announced in 2025 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.1548% across the stellar disk), this world measures 2.01 Earth radii and has a measured mass of 4.7 Earth masses. Combining its mass and radius yields a mean bulk density of 3.19 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.16 g⊕ (11.38 m/s²), and an escape velocity of 17.1 km/s.
In its orbital architecture around TOI-4364, TOI-4364 b completes one full revolution every 5.424 Earth days at a semi-major axis of 0.04753 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 95.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.29, swinging from 0.0337 AU at periapsis out to 0.0613 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 488 K (+215°C / +419°F) and receiving 13.33 S⊕ (~18,146 W/m²), TOI-4364 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4364 is classified as a low-mass red dwarf of spectral type M4 V with an effective photospheric temperature of 3,528 K, a radius of 0.4684 R☉, a mass of 0.487 M☉, an estimated bolometric luminosity of 0.03 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.71 Gyr and a metallicity of [Fe/H] = 0.148 dex (metal-rich relative to the Sun). From Earth, TOI-4364 shines at apparent V-band magnitude 13.564 (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-4364 |
| Spectral Type | M4 V |
| Effective Temp (Teff) | 3,528 K |
| Stellar Radius | 0.4684 R☉ |
| Stellar Mass | 0.4870 M☉ |
| Bolometric Luminosity | 0.03 L☉ |
| Metallicity [Fe/H] | 0.148 dex |
| Stellar Age | 0.710 Gyr |
| Apparent Magnitude | V: 13.564 · G: 12.555 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.047530 AU |
| Orbital Period | 5.424 days |
| Mean Orbital Velocity | 95.3 km/s |
| Orbital Eccentricity (e) | 0.29000 |
| Orbital Inclination (i) | 88.6800° |
| Mean Bulk Density | 3.19 g/cm³ (17.1 km/s vesc) |
| Insolation Flux | 13.3328 S⊕ (~18,146 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 143.400 LY (43.966 pc) |