TOI-220 b
Astrophysical Synthesis & Habitability Characterization
TOI-220 b is a confirmed sub-neptune exoplanet orbiting the star TOI-220, located approximately 296 light-years (90.74 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 0.1048% across the stellar disk), this world measures 3.03 Earth radii (0.27 Jupiter radii) and has a measured mass of 13.8 Earth masses. Combining its mass and radius yields a mean bulk density of 2.74 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.5 g⊕ (14.71 m/s²), and an escape velocity of 23.9 km/s.
In its orbital architecture around TOI-220, TOI-220 b completes one full revolution every 10.695 Earth days at a semi-major axis of 0.08911 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 90.6 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.032 (ranging from 0.0863 AU at periapsis to 0.092 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 805 K (+532°C / +990°F) and receiving 137.73 S⊕ (~187,444 W/m²), TOI-220 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-220 is classified as an orange K-type star of spectral type K0 V with an effective photospheric temperature of 5,298 K, a radius of 0.858 R☉, a mass of 0.825 M☉, an estimated bolometric luminosity of 0.52 L☉. Stellar evolution modeling indicates an estimated stellar age of 10.1 Gyr and a metallicity of [Fe/H] = -0.217 dex (metal-poor relative to the Sun). From Earth, TOI-220 shines at apparent V-band magnitude 10.466 (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-220 |
| Spectral Type | K0 V |
| Effective Temp (Teff) | 5,298 K |
| Stellar Radius | 0.8580 R☉ |
| Stellar Mass | 0.8250 M☉ |
| Bolometric Luminosity | 0.52 L☉ |
| Metallicity [Fe/H] | -0.217 dex |
| Stellar Age | 10.100 Gyr |
| Apparent Magnitude | V: 10.466 · G: 10.190 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.089110 AU |
| Orbital Period | 10.695 days |
| Mean Orbital Velocity | 90.6 km/s |
| Orbital Eccentricity (e) | 0.03200 |
| Orbital Inclination (i) | 87.8800° |
| Mean Bulk Density | 2.74 g/cm³ (23.9 km/s vesc) |
| Insolation Flux | 137.7252 S⊕ (~187,444 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 296.000 LY (90.740 pc) |