HD 29985 b
Astrophysical Synthesis & Habitability Characterization
HD 29985 b is a confirmed gas giant exoplanet orbiting the star HD 29985, located approximately 102 light-years (31.27 parsecs) from the Solar System. First announced in 2022 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.8 Earth radii (1.14 Jupiter radii) and has a measured mass of 1739.475 Earth masses (5.47 Jupiter masses). Combining its mass and radius yields a mean bulk density of 4.57 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 10.62 g⊕ (104.15 m/s²), and an escape velocity of 130.4 km/s.
In its orbital architecture around HD 29985, HD 29985 b completes one full revolution every 20608.14 Earth days (56.42Julian years) at a semi-major axis of 13.39 AU (a wide outer-system orbit beyond Jupiter's 5.20 AU distance in our Solar System). Its mean orbital velocity is approximately 7.1 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.261, swinging from 9.8952 AU at periapsis out to 16.8848 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 47 K (-226°C / -375°F) and an incident flux of 0.00 S⊕ (~1 W/m²), surface water and volatile species on HD 29985 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 29985 is classified as a stellar host with an effective photospheric temperature of 4,678 K, a radius of 0.5747 R☉, a mass of 0.75 M☉, an estimated bolometric luminosity of 0.142 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.22 dex (metal-poor relative to the Sun). From Earth, HD 29985 shines at apparent V-band magnitude 9.98 (accessible to binoculars and small amateur telescopes) in the Southern 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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 29985 |
| Spectral Type | Unclassified |
| Effective Temp (Teff) | 4,678 K |
| Stellar Radius | 0.5747 R☉ |
| Stellar Mass | 0.7500 M☉ |
| Bolometric Luminosity | 0.142 L☉ |
| Metallicity [Fe/H] | -0.220 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 9.980 · G: 9.472 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 13.390000 AU |
| Orbital Period | 20608.14 days |
| Mean Orbital Velocity | 7.1 km/s |
| Orbital Eccentricity (e) | 0.26100 |
| Orbital Inclination (i) | 52.6580° |
| Mean Bulk Density | 4.57 g/cm³ (130.4 km/s vesc) |
| Insolation Flux | 0.0008 S⊕ (~1 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 102.000 LY (31.271 pc) |