TOI-4201 b
Astrophysical Synthesis & Habitability Characterization
TOI-4201 b is a confirmed gas giant exoplanet orbiting the star TOI-4201, located approximately 616.5 light-years (189.01 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 3.9602% across the stellar disk), this world measures 13.675 Earth radii (1.22 Jupiter radii) and has a measured mass of 788.214 Earth masses (2.48 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.7 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 4.21 g⊕ (41.29 m/s²), and an escape velocity of 84.9 km/s.
In its orbital architecture around TOI-4201, TOI-4201 b completes one full revolution every 3.582 Earth days at a semi-major axis of 0.04 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 121.5 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.041 (ranging from 0.0384 AU at periapsis to 0.0416 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 725 K (+452°C / +846°F) and receiving 45.20 S⊕ (~61,517 W/m²), TOI-4201 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-4201 is classified as a low-mass red dwarf of spectral type M1.0+/-0.5 with an effective photospheric temperature of 3,794 K, a radius of 0.63 R☉, a mass of 0.61 M☉, an estimated bolometric luminosity of 0.074 L☉. Stellar evolution modeling indicates an estimated stellar age of 1.4 Gyr and a metallicity of [Fe/H] = 0.52 dex (metal-rich relative to the Sun). From Earth, TOI-4201 shines at apparent V-band magnitude 15.163 (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-4201 |
| Spectral Type | M1.0+/-0.5 |
| Effective Temp (Teff) | 3,794 K |
| Stellar Radius | 0.6300 R☉ |
| Stellar Mass | 0.6100 M☉ |
| Bolometric Luminosity | 0.074 L☉ |
| Metallicity [Fe/H] | 0.520 dex |
| Stellar Age | 1.400 Gyr |
| Apparent Magnitude | V: 15.163 · G: 14.500 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.040000 AU |
| Orbital Period | 3.582 days |
| Mean Orbital Velocity | 121.5 km/s |
| Orbital Eccentricity (e) | 0.04100 |
| Orbital Inclination (i) | 88.0000° |
| Mean Bulk Density | 1.7 g/cm³ (84.9 km/s vesc) |
| Insolation Flux | 45.2000 S⊕ (~61,517 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 616.500 LY (189.011 pc) |