EPIC 249893012 d
Astrophysical Synthesis & Habitability Characterization
EPIC 249893012 d is a confirmed sub-neptune exoplanet orbiting the star EPIC 249893012, located approximately 1047.9 light-years (321.3 parsecs) from the Solar System. First announced in 2020 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0446% across the stellar disk), this world measures 3.94 Earth radii (0.35 Jupiter radii) and has a measured mass of 10.18 Earth masses. Combining its mass and radius yields a mean bulk density of 0.92 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 0.66 g⊕ (6.47 m/s²), and an escape velocity of 18 km/s.
In its orbital architecture around EPIC 249893012, EPIC 249893012 d completes one full revolution every 35.747 Earth days at a semi-major axis of 0.22 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 67 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.15 carries the world between 0.187 AU at periapsis and 0.253 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 752 K (+479°C / +894°F) and receiving 53.00 S⊕ (~72,133 W/m²), EPIC 249893012 d orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star EPIC 249893012 is classified as a solar-type yellow star of spectral type G8 IV/V with an effective photospheric temperature of 5,430 K, a radius of 1.71 R☉, a mass of 1.05 M☉, an estimated bolometric luminosity of 2.281 L☉. Stellar evolution modeling indicates an estimated stellar age of 9 Gyr and a metallicity of [Fe/H] = 0.2 dex (metal-rich relative to the Sun). From Earth, EPIC 249893012 shines at apparent V-band magnitude 11.429 (faint and requiring research-grade or CCD telescopic photometry) in the Southern celestial hemisphere. The EPIC 249893012 system is a multi-planet architecture hosting 3 confirmed worlds, with EPIC 249893012 d sharing its stellar neighborhood alongside EPIC 249893012 b, EPIC 249893012 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 | EPIC 249893012 |
| Spectral Type | G8 IV/V |
| Effective Temp (Teff) | 5,430 K |
| Stellar Radius | 1.7100 R☉ |
| Stellar Mass | 1.0500 M☉ |
| Bolometric Luminosity | 2.281 L☉ |
| Metallicity [Fe/H] | 0.200 dex |
| Stellar Age | 9.000 Gyr |
| Apparent Magnitude | V: 11.429 · G: 11.402 |
| System Architecture | 1 Star, 3 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.220000 AU |
| Orbital Period | 35.747 days |
| Mean Orbital Velocity | 67 km/s |
| Orbital Eccentricity (e) | 0.15000 |
| Orbital Inclination (i) | 89.4700° |
| Mean Bulk Density | 0.92 g/cm³ (18 km/s vesc) |
| Insolation Flux | 53.0000 S⊕ (~72,133 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1047.900 LY (321.296 pc) |