BD-210397 c
Astrophysical Synthesis & Habitability Characterization
BD-210397 c 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 12.9 Earth radii (1.15 Jupiter radii) and has a measured mass of 1525.576 Earth masses (4.8 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.92 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 9.17 g⊕ (89.93 m/s²), and an escape velocity of 121.6 km/s.
In its orbital architecture around BD-210397, BD-210397 c completes one full revolution every 6240 Earth days (17.08Julian years) at a semi-major axis of 5.9 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 10.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.43, swinging from 3.363 AU at periapsis out to 8.437 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 70 K (-203°C / -333°F) and an incident flux of 0.00 S⊕ (~5 W/m²), surface water and volatile species on BD-210397 c 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 0.69 M☉, an estimated bolometric luminosity of 0.135 L☉. Stellar evolution modeling indicates an estimated stellar age of 4 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 c sharing its stellar neighborhood alongside BD-210397 b.
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 | 0.6900 M☉ |
| Bolometric Luminosity | 0.135 L☉ |
| Metallicity [Fe/H] | 0.120 dex |
| Stellar Age | 4.000 Gyr |
| Apparent Magnitude | V: 9.840 · G: 9.260 |
| System Architecture | 1 Star, 2 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 5.900000 AU |
| Orbital Period | 6240 days |
| Mean Orbital Velocity | 10.3 km/s |
| Orbital Eccentricity (e) | 0.43000 |
| Orbital Inclination (i) | 33.0000° |
| Mean Bulk Density | 3.92 g/cm³ (121.6 km/s vesc) |
| Insolation Flux | 0.0039 S⊕ (~5 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 77.400 LY (23.732 pc) |