TOI-201 d
Astrophysical Synthesis & Habitability Characterization
TOI-201 d is a confirmed super-earth exoplanet orbiting the star TOI-201, located approximately 371.2 light-years (113.83 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 0.0095% across the stellar disk), this world measures 1.39 Earth radii and has a measured mass of 5.8 Earth masses. Combining its mass and radius yields a mean bulk density of 11.91 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3 g⊕ (29.42 m/s²), and an escape velocity of 22.8 km/s.
In its orbital architecture around TOI-201, TOI-201 d completes one full revolution every 5.849 Earth days at a semi-major axis of 0.0698 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 129.8 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.3, swinging from 0.0489 AU at periapsis out to 0.0907 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 1237 K (+964°C / +1767°F) and receiving 389.67 S⊕ (~530,340 W/m²), TOI-201 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-201 is classified as a warm F-type star of spectral type F with an effective photospheric temperature of 6,423 K, a radius of 1.31 R☉, a mass of 1.32 M☉, an estimated bolometric luminosity of 2.62 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.666 Gyr and a metallicity of [Fe/H] = 0.24 dex (metal-rich relative to the Sun). From Earth, TOI-201 shines at apparent V-band magnitude 9.07 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The TOI-201 system is a multi-planet architecture hosting 3 confirmed worlds, with TOI-201 d sharing its stellar neighborhood alongside TOI-201 b, TOI-201 c.
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-201 |
| Spectral Type | F |
| Effective Temp (Teff) | 6,423 K |
| Stellar Radius | 1.3100 R☉ |
| Stellar Mass | 1.3200 M☉ |
| Bolometric Luminosity | 2.62 L☉ |
| Metallicity [Fe/H] | 0.240 dex |
| Stellar Age | 0.666 Gyr |
| Apparent Magnitude | V: 9.070 · G: 8.940 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.069800 AU |
| Orbital Period | 5.849 days |
| Mean Orbital Velocity | 129.8 km/s |
| Orbital Eccentricity (e) | 0.30000 |
| Orbital Inclination (i) | 91.7000° |
| Mean Bulk Density | 11.91 g/cm³ (22.8 km/s vesc) |
| Insolation Flux | 389.6690 S⊕ (~530,340 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 371.200 LY (113.825 pc) |