TOI-122 b
Astrophysical Synthesis & Habitability Characterization
TOI-122 b is a confirmed sub-neptune exoplanet orbiting the star TOI-122, located approximately 202.6 light-years (62.12 parsecs) from the Solar System. First announced in 2020 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.5574% across the stellar disk), this world measures 2.72 Earth radii and has a measured mass of 7.85 Earth masses. Combining its mass and radius yields a mean bulk density of 2.15 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 19 km/s.
In its orbital architecture around TOI-122, TOI-122 b completes one full revolution every 5.078 Earth days at a semi-major axis of 0.0392 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 84 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 471 K (+198°C / +388°F) and receiving 8.80 S⊕ (~11,977 W/m²), TOI-122 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-122 is classified as a low-mass red dwarf of spectral type M3 V with an effective photospheric temperature of 3,403 K, a radius of 0.334 R☉, a mass of 0.312 M☉, an estimated bolometric luminosity of 0.013 L☉. Stellar evolution modeling indicates an estimated stellar age of 2 Gyr. From Earth, TOI-122 shines at apparent V-band magnitude 15.526 (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-122 |
| Spectral Type | M3 V |
| Effective Temp (Teff) | 3,403 K |
| Stellar Radius | 0.3340 R☉ |
| Stellar Mass | 0.3120 M☉ |
| Bolometric Luminosity | 0.013 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | 2.000 Gyr |
| Apparent Magnitude | V: 15.526 · G: 14.336 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.039200 AU |
| Orbital Period | 5.078 days |
| Mean Orbital Velocity | 84 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.4000° |
| Mean Bulk Density | 2.15 g/cm³ (19 km/s vesc) |
| Insolation Flux | 8.8000 S⊕ (~11,977 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 202.600 LY (62.118 pc) |