TOI-406 c
Astrophysical Synthesis & Habitability Characterization
TOI-406 c is a confirmed super-earth exoplanet orbiting the star TOI-406, located approximately 101.3 light-years (31.06 parsecs) from the Solar System. First announced in 2024 by Transiting Exoplanet Survey Satellite (TESS) using the Transit detection technique (producing an estimated primary transit depth of 0.0871% across the stellar disk), this world measures 1.32 Earth radii and has a measured mass of 2.08 Earth masses. Combining its mass and radius yields a mean bulk density of 4.99 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.19 g⊕ (11.67 m/s²), and an escape velocity of 14 km/s.
In its orbital architecture around TOI-406, TOI-406 c completes one full revolution every 3.307 Earth days at a semi-major axis of 0.0322 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 105.9 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.032 (ranging from 0.0312 AU at periapsis to 0.0332 AU at apoapsis), the planet experiences minimal orbital distance variation.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 584 K (+311°C / +592°F) and receiving 19.00 S⊕ (~25,859 W/m²), TOI-406 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star TOI-406 is classified as a low-mass red dwarf of spectral type M3 with an effective photospheric temperature of 3,392 K, a radius of 0.41 R☉, a mass of 0.408 M☉, an estimated bolometric luminosity of 0.02 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.02 dex (near-solar heavy-element abundance). From Earth, TOI-406 shines at apparent V-band magnitude 13.773 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The TOI-406 system is a multi-planet architecture hosting 2 confirmed worlds, with TOI-406 c sharing its stellar neighborhood alongside TOI-406.01.
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-406 |
| Spectral Type | M3 |
| Effective Temp (Teff) | 3,392 K |
| Stellar Radius | 0.4100 R☉ |
| Stellar Mass | 0.4080 M☉ |
| Bolometric Luminosity | 0.02 L☉ |
| Metallicity [Fe/H] | -0.020 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 13.773 · G: 12.553 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.032200 AU |
| Orbital Period | 3.307 days |
| Mean Orbital Velocity | 105.9 km/s |
| Orbital Eccentricity (e) | 0.03200 |
| Orbital Inclination (i) | 87.6000° |
| Mean Bulk Density | 4.99 g/cm³ (14 km/s vesc) |
| Insolation Flux | 19.0000 S⊕ (~25,859 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 101.300 LY (31.060 pc) |