TOI-2018 b
Astrophysical Synthesis & Habitability Characterization
TOI-2018 b is a confirmed sub-neptune exoplanet orbiting the star TOI-2018, located approximately 91.3 light-years (28 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 0.1125% across the stellar disk), this world measures 2.268 Earth radii and has a measured mass of 9.2 Earth masses. Combining its mass and radius yields a mean bulk density of 4.35 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.79 g⊕ (17.55 m/s²), and an escape velocity of 22.5 km/s.
In its orbital architecture around TOI-2018, TOI-2018 b completes one full revolution every 7.436 Earth days. 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 576 K (+303°C / +577°F) and receiving 26.08 S⊕ (~35,489 W/m²), TOI-2018 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-2018 is classified as an orange K-type star of spectral type K V with an effective photospheric temperature of 4,174 K, a radius of 0.62 R☉, a mass of 0.57 M☉, an estimated bolometric luminosity of 0.105 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.58 dex (metal-poor relative to the Sun). From Earth, TOI-2018 shines at apparent V-band magnitude 10.25 (faint and requiring research-grade or CCD telescopic photometry) in the Northern 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-2018 |
| Spectral Type | K V |
| Effective Temp (Teff) | 4,174 K |
| Stellar Radius | 0.6200 R☉ |
| Stellar Mass | 0.5700 M☉ |
| Bolometric Luminosity | 0.105 L☉ |
| Metallicity [Fe/H] | -0.580 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 10.250 · G: 9.720 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 7.436 days |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 88.5200° |
| Mean Bulk Density | 4.35 g/cm³ (22.5 km/s vesc) |
| Insolation Flux | 26.0758 S⊕ (~35,489 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 91.300 LY (27.996 pc) |