EPIC 229004835 b
Astrophysical Synthesis & Habitability Characterization
EPIC 229004835 b is a confirmed sub-neptune exoplanet orbiting the star EPIC 229004835, located approximately 397.8 light-years (121.97 parsecs) from the Solar System. First announced in 2023 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0458% across the stellar disk), this world measures 2.332 Earth radii and has a measured mass of 10.4 Earth masses. Combining its mass and radius yields a mean bulk density of 4.52 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.91 g⊕ (18.73 m/s²), and an escape velocity of 23.6 km/s.
In its orbital architecture around EPIC 229004835, EPIC 229004835 b completes one full revolution every 16.141 Earth days at a semi-major axis of 0.1237 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 83.4 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.23 carries the world between 0.0952 AU at periapsis and 0.1522 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 804 K (+531°C / +988°F) and receiving 69.70 S⊕ (~94,862 W/m²), EPIC 229004835 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star EPIC 229004835 is classified as a stellar host with an effective photospheric temperature of 5,868 K, a radius of 0.999 R☉, a mass of 0.97 M☉, an estimated bolometric luminosity of 1.062 L☉. Stellar evolution modeling indicates an estimated stellar age of 4.9 Gyr and a metallicity of [Fe/H] = -0.12 dex (metal-poor relative to the Sun). From Earth, EPIC 229004835 shines at apparent V-band magnitude 10.23 (faint and requiring research-grade or CCD telescopic photometry) in the Southern 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 229004835 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 5,868 K |
| Stellar Radius | 0.9990 R☉ |
| Stellar Mass | 0.9700 M☉ |
| Bolometric Luminosity | 1.062 L☉ |
| Metallicity [Fe/H] | -0.120 dex |
| Stellar Age | 4.900 Gyr |
| Apparent Magnitude | V: 10.230 · G: 10.049 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.123700 AU |
| Orbital Period | 16.141 days |
| Mean Orbital Velocity | 83.4 km/s |
| Orbital Eccentricity (e) | 0.23000 |
| Orbital Inclination (i) | 88.0800° |
| Mean Bulk Density | 4.52 g/cm³ (23.6 km/s vesc) |
| Insolation Flux | 69.7000 S⊕ (~94,862 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 397.800 LY (121.971 pc) |