BD+20 594 b
Astrophysical Synthesis & Habitability Characterization
BD+20 594 b is a confirmed sub-neptune exoplanet orbiting the star BD+20 594, located approximately 585.3 light-years (179.46 parsecs) from the Solar System. First announced in 2016 by K2 using the Transit detection technique (producing an estimated primary transit depth of 0.0479% across the stellar disk), this world measures 2.578 Earth radii and has a measured mass of 22.248 Earth masses. Combining its mass and radius yields a mean bulk density of 7.16 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 3.35 g⊕ (32.85 m/s²), and an escape velocity of 32.9 km/s.
In its orbital architecture around BD+20 594, BD+20 594 b completes one full revolution every 41.686 Earth days at a semi-major axis of 0.241 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 62.9 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 546 K (+273°C / +523°F) and receiving 15.15 S⊕ (~20,621 W/m²), BD+20 594 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star BD+20 594 is classified as a solar-type yellow star of spectral type G with an effective photospheric temperature of 5,766 K, a radius of 1.08 R☉, a mass of 1.67 M☉, an estimated bolometric luminosity of 1.157 L☉. Stellar evolution modeling indicates an estimated stellar age of 3.34 Gyr and a metallicity of [Fe/H] = -0.15 dex (metal-poor relative to the Sun). From Earth, BD+20 594 shines at apparent V-band magnitude 10.849 (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 | BD+20 594 |
| Spectral Type | G |
| Effective Temp (Teff) | 5,766 K |
| Stellar Radius | 1.0800 R☉ |
| Stellar Mass | 1.6700 M☉ |
| Bolometric Luminosity | 1.157 L☉ |
| Metallicity [Fe/H] | -0.150 dex |
| Stellar Age | 3.340 Gyr |
| Apparent Magnitude | V: 10.849 · G: 10.864 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.241000 AU |
| Orbital Period | 41.686 days |
| Mean Orbital Velocity | 62.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.5500° |
| Mean Bulk Density | 7.16 g/cm³ (32.9 km/s vesc) |
| Insolation Flux | 15.1513 S⊕ (~20,621 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 585.300 LY (179.461 pc) |