TOI-1201 b
Astrophysical Synthesis & Habitability Characterization
TOI-1201 b is a confirmed sub-neptune exoplanet orbiting the star TOI-1201, located approximately 123.6 light-years (37.89 parsecs) from the Solar System. First announced in 2021 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.19% across the stellar disk), this world measures 2.415 Earth radii and has a measured mass of 6.28 Earth masses. Combining its mass and radius yields a mean bulk density of 2.46 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.08 g⊕ (10.59 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around TOI-1201, TOI-1201 b completes one full revolution every 2.492 Earth days at a semi-major axis of 0.0287 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 125.3 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 703 K (+430°C / +806°F) and receiving 40.60 S⊕ (~55,257 W/m²), TOI-1201 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-1201 is classified as a low-mass red dwarf of spectral type M2.0 V with an effective photospheric temperature of 3,476 K, a radius of 0.508 R☉, a mass of 0.512 M☉, an estimated bolometric luminosity of 0.034 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = 0.05 dex (near-solar heavy-element abundance). From Earth, TOI-1201 shines at apparent V-band magnitude 12.26 (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-1201 |
| Spectral Type | M2.0 V |
| Effective Temp (Teff) | 3,476 K |
| Stellar Radius | 0.5080 R☉ |
| Stellar Mass | 0.5120 M☉ |
| Bolometric Luminosity | 0.034 L☉ |
| Metallicity [Fe/H] | 0.050 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.260 · G: 12.097 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.028700 AU |
| Orbital Period | 2.492 days |
| Mean Orbital Velocity | 125.3 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.1100° |
| Mean Bulk Density | 2.46 g/cm³ (18 km/s vesc) |
| Insolation Flux | 40.6000 S⊕ (~55,257 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 123.600 LY (37.887 pc) |