HD 29021 b
Astrophysical Synthesis & Habitability Characterization
HD 29021 b is a confirmed gas giant exoplanet orbiting the star HD 29021, located approximately 101.1 light-years (30.99 parsecs) from the Solar System. First announced in 2017 by Haute-Provence 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 1420.693 Earth masses (4.47 Jupiter masses). Combining its mass and radius yields a mean bulk density of 3.65 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 8.54 g⊕ (83.75 m/s²), and an escape velocity of 117.4 km/s.
In its orbital architecture around HD 29021, HD 29021 b completes one full revolution every 1365 Earth days (3.74Julian years) at a semi-major axis of 2.294 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 18.3 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.453, swinging from 1.2548 AU at periapsis out to 3.3332 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
❄️ Thermal Regime (Cryogenic Zone): With an equilibrium temperature of 163 K (-110°C / -166°F) and an incident flux of 0.13 S⊕ (~170 W/m²), surface water and volatile species on HD 29021 b would remain locked in cryogenic ice phases unless warmed by subsurface tidal or radiogenic heating.
The host star HD 29021 is classified as a solar-type yellow star of spectral type G5 with an effective photospheric temperature of 5,560 K, a radius of 0.85 R☉, a mass of 0.86 M☉, an estimated bolometric luminosity of 0.619 L☉. Stellar evolution modeling indicates an estimated stellar age of 5.5 Gyr and a metallicity of [Fe/H] = -0.3 dex (metal-poor relative to the Sun). From Earth, HD 29021 shines at apparent V-band magnitude 7.76 (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: Haute-Provence Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | HD 29021 |
| Spectral Type | G5 |
| Effective Temp (Teff) | 5,560 K |
| Stellar Radius | 0.8500 R☉ |
| Stellar Mass | 0.8600 M☉ |
| Bolometric Luminosity | 0.619 L☉ |
| Metallicity [Fe/H] | -0.300 dex |
| Stellar Age | 5.500 Gyr |
| Apparent Magnitude | V: 7.760 · G: 7.586 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.294000 AU |
| Orbital Period | 1365 days |
| Mean Orbital Velocity | 18.3 km/s |
| Orbital Eccentricity (e) | 0.45300 |
| Orbital Inclination (i) | 33.7000° |
| Mean Bulk Density | 3.65 g/cm³ (117.4 km/s vesc) |
| Insolation Flux | 0.1252 S⊕ (~170 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 101.100 LY (30.994 pc) |