BD+48 738 b
Astrophysical Synthesis & Habitability Characterization
BD+48 738 b is a confirmed gas giant exoplanet orbiting the star BD+48 738, located approximately 2842.4 light-years (871.49 parsecs) from the Solar System. First announced in 2011 by McDonald Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.9 Earth radii (1.24 Jupiter radii) and has a measured mass of 289.225 Earth masses (0.91 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.59 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.5 g⊕ (14.71 m/s²), and an escape velocity of 51 km/s.
In its orbital architecture around BD+48 738, BD+48 738 b completes one full revolution every 392.6 Earth days (1.07Julian years) at a semi-major axis of 1 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 27.7 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.2 carries the world between 0.8 AU at periapsis and 1.2 AU at apoapsis, driving measurable seasonal insolation cycles.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 706 K (+433°C / +811°F) and receiving 48.98 S⊕ (~66,659 W/m²), BD+48 738 b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
The host star BD+48 738 is classified as an orange K-type star of spectral type K0 III with an effective photospheric temperature of 4,414 K, a radius of 11 R☉, a mass of 0.74 M☉, an estimated bolometric luminosity of 41.21 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.2 dex (metal-poor relative to the Sun). From Earth, BD+48 738 shines at apparent V-band magnitude 9.139 (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+48 738 |
| Spectral Type | K0 III |
| Effective Temp (Teff) | 4,414 K |
| Stellar Radius | 11.0000 R☉ |
| Stellar Mass | 0.7400 M☉ |
| Bolometric Luminosity | 41.21 L☉ |
| Metallicity [Fe/H] | -0.200 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.139 · G: 8.656 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 1.000000 AU |
| Orbital Period | 392.6 days |
| Mean Orbital Velocity | 27.7 km/s |
| Orbital Eccentricity (e) | 0.20000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.59 g/cm³ (51 km/s vesc) |
| Insolation Flux | 48.9779 S⊕ (~66,659 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 2842.400 LY (871.493 pc) |