BD-210397 b
Astrophysical Synthesis & Habitability Characterization
BD-210397 b is a confirmed gas giant exoplanet orbiting the star BD-210397, located approximately 77.4 light-years (23.73 parsecs) from the Solar System. First announced in 2023 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 14 Earth radii (1.25 Jupiter radii) and has a measured mass of 214 Earth masses (0.67 Jupiter masses). Combining its mass and radius yields a mean bulk density of 0.43 g/cm³ (a low bulk density dominated by an extended hydrogen-helium gaseous envelope), a surface gravity of 1.09 g⊕ (10.69 m/s²), and an escape velocity of 43.7 km/s.
In its orbital architecture around BD-210397, BD-210397 b completes one full revolution every 1891 Earth days (5.18Julian years) at a semi-major axis of 2.63 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 15.1 km/s (compared to Earth's 29.8 km/s). Its moderate orbital eccentricity of e = 0.1 carries the world between 2.367 AU at periapsis and 2.893 AU at apoapsis, driving measurable seasonal insolation cycles.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 104 K (-169°C / -272°F) and an incident flux of 0.02 S⊕ (~27 W/m²), surface water and volatile species on BD-210397 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star BD-210397 is classified as an orange K-type star of spectral type K7 V with an effective photospheric temperature of 4,051 K, a radius of 0.747 R☉, a mass of 0.679 M☉, an estimated bolometric luminosity of 0.135 L☉. Stellar evolution modeling indicates an estimated stellar age of 6.2 Gyr and a metallicity of [Fe/H] = 0.12 dex (metal-rich relative to the Sun). From Earth, BD-210397 shines at apparent V-band magnitude 9.84 (accessible to binoculars and small amateur telescopes) in the Southern celestial hemisphere. The BD-210397 system is a multi-planet architecture hosting 2 confirmed worlds, with BD-210397 b sharing its stellar neighborhood alongside BD-210397 c.
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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | BD-210397 |
| Spectral Type | K7 V |
| Effective Temp (Teff) | 4,051 K |
| Stellar Radius | 0.7470 R☉ |
| Stellar Mass | 0.6790 M☉ |
| Bolometric Luminosity | 0.135 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 6.200 Gyr |
| Apparent Magnitude | V: 9.840 · G: 9.260 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.630000 AU |
| Orbital Period | 1891 days |
| Mean Orbital Velocity | 15.1 km/s |
| Orbital Eccentricity (e) | 0.10000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 0.43 g/cm³ (43.7 km/s vesc) |
| Insolation Flux | 0.0200 S⊕ (~27 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 77.400 LY (23.732 pc) |