K2-400 b
Astrophysical Synthesis & Habitability Characterization
K2-400 b is a confirmed terrestrial exoplanet orbiting the star K2-400, located approximately 203.5 light-years (62.38 parsecs) from the Solar System. First announced in 2022 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0779% across the stellar disk), this world measures 1.163 Earth radii and has a measured mass of 1.67 Earth masses. Combining its mass and radius yields a mean bulk density of 5.85 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.23 g⊕ (12.06 m/s²), and an escape velocity of 13.4 km/s.
In its orbital architecture around K2-400, K2-400 b completes one full revolution every 3.865 Earth days.
ℹ️ Thermal & Atmospheric Regime: Current photometric and spectroscopic constraints for K2-400 b place it outside the conservative habitable zone definition pending further atmospheric characterization.
The host star K2-400 is classified as a low-mass red dwarf of spectral type M3 with an effective photospheric temperature of 3,578 K, a radius of 0.382 R☉, a mass of 0.374 M☉, an estimated bolometric luminosity of 0.021 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.051 dex (near-solar heavy-element abundance). From Earth, K2-400 shines at apparent V-band magnitude 15.108 (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: K2 · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | K2-400 |
| Spectral Type | M3 |
| Effective Temp (Teff) | 3,578 K |
| Stellar Radius | 0.3820 R☉ |
| Stellar Mass | 0.3740 M☉ |
| Bolometric Luminosity | 0.021 L☉ |
| Metallicity [Fe/H] | -0.051 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 15.108 · G: 13.990 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 3.865 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 5.85 g/cm³ (13.4 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 203.500 LY (62.380 pc) |