K2-381 d
Astrophysical Synthesis & Habitability Characterization
K2-381 d is a confirmed super-earth exoplanet orbiting the star K2-381, located approximately 475.2 light-years (145.7 parsecs) from the Solar System. First announced in 2022 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0526% across the stellar disk), this world measures 1.689 Earth radii and has a measured mass of 3.5 Earth masses. Combining its mass and radius yields a mean bulk density of 4.01 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 16.1 km/s.
In its orbital architecture around K2-381, K2-381 d completes one full revolution every 26.803 Earth days.
ℹ️ Thermal & Atmospheric Regime: Current photometric and spectroscopic constraints for K2-381 d place it outside the conservative habitable zone definition pending further atmospheric characterization.
The host star K2-381 is classified as a stellar host with an effective photospheric temperature of 4,473 K, a radius of 0.675 R☉, a mass of 0.754 M☉, an estimated bolometric luminosity of 0.164 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.244 dex (metal-poor relative to the Sun). From Earth, K2-381 shines at apparent V-band magnitude 12.883 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The K2-381 system is a multi-planet architecture hosting 3 confirmed worlds, with K2-381 d sharing its stellar neighborhood alongside K2-381 b, K2-381 c.
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 | K2-381 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,473 K |
| Stellar Radius | 0.6750 R☉ |
| Stellar Mass | 0.7540 M☉ |
| Bolometric Luminosity | 0.164 L☉ |
| Metallicity [Fe/H] | -0.244 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.883 · G: 12.637 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | — |
| Orbital Period | 26.803 days |
| Orbital Eccentricity (e) | Circular (0.00) |
| Orbital Inclination (i) | 89.4780° |
| Mean Bulk Density | 4.01 g/cm³ (16.1 km/s vesc) |
| Insolation Flux | — |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 475.200 LY (145.701 pc) |