TOI-4638.01
Astrophysical Synthesis & Habitability Characterization
TOI-4638.01 is a confirmed sub-neptune exoplanet orbiting the star TOI-4638, located approximately 548.8 light-years (168.25 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0903% across the stellar disk), this world measures 2.933 Earth radii and has a measured mass of 8.92 Earth masses. Combining its mass and radius yields a mean bulk density of 1.95 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.04 g⊕ (10.2 m/s²), and an escape velocity of 19.5 km/s.
In its orbital architecture around TOI-4638, TOI-4638.01 completes one full revolution every 10.284 Earth days at a semi-major axis of 0.093013 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 98.4 km/s (compared to Earth's 29.8 km/s).
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 780 K (+507°C / +945°F) and receiving 87.81 S⊕ (~119,509 W/m²), TOI-4638.01 orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4638 is classified as a stellar host with an effective photospheric temperature of 5,700 K, a radius of 0.895 R☉, a mass of 1.02 M☉, an estimated bolometric luminosity of 0.759 L☉. From Earth, TOI-4638 shines at apparent V-band magnitude 11.657 (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-4638 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,700 K |
| Stellar Radius | 0.8950 R☉ |
| Stellar Mass | 1.0200 M☉ |
| Bolometric Luminosity | 0.759 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 11.657 · G: 11.210 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.093013 AU |
| Orbital Period | 10.284 days |
| Mean Orbital Velocity | 98.4 km/s |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.95 g/cm³ (19.5 km/s vesc) |
| Insolation Flux | 87.8100 S⊕ (~119,509 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 548.800 LY (168.248 pc) |