TOI-213 b
Astrophysical Synthesis & Habitability Characterization
TOI-213 b is a confirmed sub-neptune exoplanet orbiting the star TOI-213, located approximately 177.2 light-years (54.33 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 0.1258% across the stellar disk), this world measures 2.6 Earth radii and has a measured mass of 7.27 Earth masses. Combining its mass and radius yields a mean bulk density of 2.28 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 18.7 km/s.
In its orbital architecture around TOI-213, TOI-213 b completes one full revolution every 23.52 Earth days. The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.600 R⊕, TOI-213 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star TOI-213 is classified as a stellar host with an effective photospheric temperature of 4,566 K, a radius of 0.6721 R☉, a mass of 0.72 M☉, an estimated bolometric luminosity of 0.176 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.08 dex (near-solar heavy-element abundance). From Earth, TOI-213 shines at apparent V-band magnitude 10.879 (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-213 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,566 K |
| Stellar Radius | 0.6721 R☉ |
| Stellar Mass | 0.7200 M☉ |
| Bolometric Luminosity | 0.176 L☉ |
| Metallicity [Fe/H] | -0.080 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 10.879 · G: 10.479 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 23.52 days |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.28 g/cm³ (18.7 km/s vesc) |
| Insolation Flux | 3.3641 S⊕ (~4,579 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 177.200 LY (54.326 pc) |