BD+20 274 b
Astrophysical Synthesis & Habitability Characterization
BD+20 274 b is a confirmed gas giant exoplanet orbiting the star BD+20 274, located approximately 4313.4 light-years (1322.51 parsecs) from the Solar System. First announced in 2012 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13 Earth radii (1.16 Jupiter radii) and has a measured mass of 1334.886 Earth masses (4.2 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.35 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 7.9 g⊕ (77.47 m/s²), and an escape velocity of 113.4 km/s.
In its orbital architecture around BD+20 274, BD+20 274 b completes one full revolution every 578.2 Earth days (1.58Julian years) at a semi-major axis of 1.3 AU (comparable to the inner terrestrial zone between Venus, Earth at 1.00 AU, and Mars at 1.52 AU). Its mean orbital velocity is approximately 24.5 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.21 carries the world between 1.027 AU at periapsis and 1.573 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 756 K (+483°C / +901°F) and receiving 53.97 S⊕ (~73,447 W/m²), BD+20 274 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star BD+20 274 is classified as an orange K-type star of spectral type K5 III with an effective photospheric temperature of 4,296 K, a radius of 17.3 R☉, a mass of 0.8 M☉, an estimated bolometric luminosity of 91.462 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.46 dex (metal-poor relative to the Sun). From Earth, BD+20 274 shines at apparent V-band magnitude 9.367 (accessible to binoculars and small amateur telescopes) 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: McDonald Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | BD+20 274 |
| Spectral Type | K5 III |
| Effective Temp (Teff) | 4,296 K |
| Stellar Radius | 17.3000 R☉ |
| Stellar Mass | 0.8000 M☉ |
| Bolometric Luminosity | 91.462 L☉ |
| Metallicity [Fe/H] | -0.460 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.367 · G: 8.916 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.300000 AU |
| Orbital Period | 578.2 days |
| Mean Orbital Velocity | 24.5 km/s |
| Orbital Eccentricity (e) | 0.21000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 3.35 g/cm³ (113.4 km/s vesc) |
| Insolation Flux | 53.9651 S⊕ (~73,447 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 4313.400 LY (1322.510 pc) |