K2-104 b
Astrophysical Synthesis & Habitability Characterization
K2-104 b is a confirmed super-earth exoplanet orbiting the star K2-104, located approximately 617.4 light-years (189.29 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.1169% across the stellar disk), this world measures 1.79 Earth radii and has a measured mass of 3.86 Earth masses. Combining its mass and radius yields a mean bulk density of 3.71 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.2 g⊕ (11.77 m/s²), and an escape velocity of 16.4 km/s.
In its orbital architecture around K2-104, K2-104 b completes one full revolution every 1.974 Earth days at a semi-major axis of 0.0242 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 133.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.09 carries the world between 0.022 AU at periapsis and 0.0264 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 798 K (+525°C / +977°F) and receiving 62.10 S⊕ (~84,518 W/m²), K2-104 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star K2-104 is classified as a low-mass red dwarf of spectral type M2.5e with an effective photospheric temperature of 3,712 K, a radius of 0.48 R☉, a mass of 0.51 M☉, an estimated bolometric luminosity of 0.039 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.79 Gyr and a metallicity of [Fe/H] = 0.18 dex (metal-rich relative to the Sun). From Earth, K2-104 shines at apparent V-band magnitude 15.989 (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 | K2-104 |
| Spectral Type | M2.5e |
| Effective Temp (Teff) | 3,712 K |
| Stellar Radius | 0.4800 R☉ |
| Stellar Mass | 0.5100 M☉ |
| Bolometric Luminosity | 0.039 L☉ |
| Metallicity [Fe/H] | 0.180 dex |
| Stellar Age | 0.790 Gyr |
| Apparent Magnitude | V: 15.989 · G: 15.396 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.024200 AU |
| Orbital Period | 1.974 days |
| Mean Orbital Velocity | 133.4 km/s |
| Orbital Eccentricity (e) | 0.09000 |
| Orbital Inclination (i) | 88.7500° |
| Mean Bulk Density | 3.71 g/cm³ (16.4 km/s vesc) |
| Insolation Flux | 62.1000 S⊕ (~84,518 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 617.400 LY (189.289 pc) |