BD+49 828 b
Astrophysical Synthesis & Habitability Characterization
BD+49 828 b is a confirmed gas giant exoplanet orbiting the star BD+49 828, located approximately 1441.7 light-years (442.04 parsecs) from the Solar System. First announced in 2015 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.5 Earth radii (1.2 Jupiter radii) and has a measured mass of 508.5 Earth masses (1.6 Jupiter masses). Combining its mass and radius yields a mean bulk density of 1.14 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 2.79 g⊕ (27.36 m/s²), and an escape velocity of 68.7 km/s.
In its orbital architecture around BD+49 828, BD+49 828 b completes one full revolution every 2590 Earth days (7.09Julian years) at a semi-major axis of 4.2 AU (corresponding to the middle-system regime between Mars at 1.52 AU and Jupiter at 5.20 AU). Its mean orbital velocity is approximately 17.6 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.35, swinging from 2.73 AU at periapsis out to 5.67 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.500 R⊕, BD+49 828 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star BD+49 828 is classified as an orange K-type star of spectral type K0 with an effective photospheric temperature of 4,943 K, a radius of 7.6 R☉, a mass of 1.52 M☉, an estimated bolometric luminosity of 30.937 L☉. Stellar evolution modeling indicates an estimated stellar age of 2.34 Gyr and a metallicity of [Fe/H] = -0.19 dex (metal-poor relative to the Sun). From Earth, BD+49 828 shines at apparent V-band magnitude 9.381 (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+49 828 |
| Spectral Type | K0 |
| Effective Temp (Teff) | 4,943 K |
| Stellar Radius | 7.6000 R☉ |
| Stellar Mass | 1.5200 M☉ |
| Bolometric Luminosity | 30.937 L☉ |
| Metallicity [Fe/H] | -0.190 dex |
| Stellar Age | 2.340 Gyr |
| Apparent Magnitude | V: 9.381 · G: 9.029 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 4.200000 AU |
| Orbital Period | 2590 days |
| Mean Orbital Velocity | 17.6 km/s |
| Orbital Eccentricity (e) | 0.35000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 1.14 g/cm³ (68.7 km/s vesc) |
| Insolation Flux | 1.6730 S⊕ (~2,277 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 1441.700 LY (442.042 pc) |