TOI-4184 b
Astrophysical Synthesis & Habitability Characterization
TOI-4184 b is a confirmed sub-neptune exoplanet orbiting the star TOI-4184, located approximately 226.2 light-years (69.37 parsecs) from the Solar System. First announced in 2023 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.901% across the stellar disk), this world measures 2.43 Earth radii and has a measured mass of 6.48 Earth masses. Combining its mass and radius yields a mean bulk density of 2.49 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.1 g⊕ (10.79 m/s²), and an escape velocity of 18.3 km/s.
In its orbital architecture around TOI-4184, TOI-4184 b completes one full revolution every 4.902 Earth days at a semi-major axis of 0.0336 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 74.6 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 412 K (+139°C / +282°F) and receiving 4.80 S⊕ (~6,533 W/m²), TOI-4184 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4184 is classified as a low-mass red dwarf of spectral type M5.5+/-0.5 with an effective photospheric temperature of 3,238 K, a radius of 0.2347 R☉, a mass of 0.2109 M☉, an estimated bolometric luminosity of 0.00543 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.7 Gyr and a metallicity of [Fe/H] = -0.27 dex (metal-poor relative to the Sun). From Earth, TOI-4184 shines at apparent V-band magnitude 17.12 (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-4184 |
| Spectral Type | M5.5+/-0.5 |
| Effective Temp (Teff) | 3,238 K |
| Stellar Radius | 0.2347 R☉ |
| Stellar Mass | 0.2109 M☉ |
| Bolometric Luminosity | 0.00543 L☉ |
| Metallicity [Fe/H] | -0.270 dex |
| Stellar Age | 6.700 Gyr |
| Apparent Magnitude | V: 17.120 · G: 15.594 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.033600 AU |
| Orbital Period | 4.902 days |
| Mean Orbital Velocity | 74.6 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.4300° |
| Mean Bulk Density | 2.49 g/cm³ (18.3 km/s vesc) |
| Insolation Flux | 4.8000 S⊕ (~6,533 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 226.200 LY (69.365 pc) |