EPIC 220674823 c
Astrophysical Synthesis & Habitability Characterization
EPIC 220674823 c is a confirmed sub-neptune exoplanet orbiting the star EPIC 220674823, located approximately 797.7 light-years (244.59 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0631% across the stellar disk), this world measures 2.712 Earth radii and has a measured mass of 7.9 Earth masses. Combining its mass and radius yields a mean bulk density of 2.18 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.07 g⊕ (10.49 m/s²), and an escape velocity of 19.1 km/s.
In its orbital architecture around EPIC 220674823, EPIC 220674823 c completes one full revolution every 13.341 Earth days at a semi-major axis of 0.1078 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 87.9 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.18 carries the world between 0.0884 AU at periapsis and 0.1272 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 838 K (+565°C / +1049°F) and receiving 70.00 S⊕ (~95,270 W/m²), EPIC 220674823 c orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star EPIC 220674823 is classified as a solar-type yellow star of spectral type G5 V with an effective photospheric temperature of 5,578 K, a radius of 0.99 R☉, a mass of 0.913 M☉, an estimated bolometric luminosity of 0.851 L☉. Stellar evolution modeling indicates an estimated stellar age of 7.5 Gyr and a metallicity of [Fe/H] = -0.005 dex (near-solar heavy-element abundance). From Earth, EPIC 220674823 shines at apparent V-band magnitude 12.101 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The EPIC 220674823 system is a multi-planet architecture hosting 2 confirmed worlds, with EPIC 220674823 c sharing its stellar neighborhood alongside EPIC 220674823 b.
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 220674823 |
| Spectral Type | G5 V |
| Effective Temp (Teff) | 5,578 K |
| Stellar Radius | 0.9900 R☉ |
| Stellar Mass | 0.9130 M☉ |
| Bolometric Luminosity | 0.851 L☉ |
| Metallicity [Fe/H] | -0.005 dex |
| Stellar Age | 7.500 Gyr |
| Apparent Magnitude | V: 12.101 · G: 11.954 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.107800 AU |
| Orbital Period | 13.341 days |
| Mean Orbital Velocity | 87.9 km/s |
| Orbital Eccentricity (e) | 0.18000 |
| Orbital Inclination (i) | 89.3400° |
| Mean Bulk Density | 2.18 g/cm³ (19.1 km/s vesc) |
| Insolation Flux | 70.0000 S⊕ (~95,270 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 797.700 LY (244.590 pc) |