EPIC 211822797 b
Astrophysical Synthesis & Habitability Characterization
EPIC 211822797 b is a confirmed super-earth exoplanet orbiting the star EPIC 211822797, located approximately 607.3 light-years (186.2 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0921% across the stellar disk), this world measures 1.92 Earth radii and has a measured mass of 4.35 Earth masses. Combining its mass and radius yields a mean bulk density of 3.39 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.18 g⊕ (11.57 m/s²), and an escape velocity of 16.8 km/s.
In its orbital architecture around EPIC 211822797, EPIC 211822797 b completes one full revolution every 21.17 Earth days at a semi-major axis of 0.1195 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 61.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.06 carries the world between 0.1123 AU at periapsis and 0.1267 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 431 K (+158°C / +316°F) and receiving 3.50 S⊕ (~4,764 W/m²), EPIC 211822797 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star EPIC 211822797 is classified as a low-mass red dwarf of spectral type M0 with an effective photospheric temperature of 4,057 K, a radius of 0.58 R☉, a mass of 0.62 M☉, an estimated bolometric luminosity of 0.082 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.79 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, EPIC 211822797 shines at apparent V-band magnitude 15.133 (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 | EPIC 211822797 |
| Spectral Type | M0 |
| Effective Temp (Teff) | 4,057 K |
| Stellar Radius | 0.5800 R☉ |
| Stellar Mass | 0.6200 M☉ |
| Bolometric Luminosity | 0.082 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 0.790 Gyr |
| Apparent Magnitude | V: 15.133 · G: 14.526 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.119500 AU |
| Orbital Period | 21.17 days |
| Mean Orbital Velocity | 61.4 km/s |
| Orbital Eccentricity (e) | 0.06000 |
| Orbital Inclination (i) | 89.7300° |
| Mean Bulk Density | 3.39 g/cm³ (16.8 km/s vesc) |
| Insolation Flux | 3.5000 S⊕ (~4,764 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 607.300 LY (186.197 pc) |