HD 68402 b
Astrophysical Synthesis & Habitability Characterization
HD 68402 b is a confirmed gas giant exoplanet orbiting the star HD 68402, located approximately 255.8 light-years (78.43 parsecs) from the Solar System. First announced in 2016 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 12.6 Earth radii (1.12 Jupiter radii) and has a measured mass of 2510.844 Earth masses (7.9 Jupiter masses). Combining its mass and radius yields a mean bulk density of 6.92 g/cm³ (an iron-enriched, high-compression rocky core), a surface gravity of 15.82 g⊕ (155.14 m/s²), and an escape velocity of 157.9 km/s.
In its orbital architecture around HD 68402, HD 68402 b completes one full revolution every 1103 Earth days (3.02Julian years) at a semi-major axis of 2.18 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 21.5 km/s (compared to Earth's 29.8 km/s). With a near-circular eccentricity of e = 0.03 (ranging from 2.1146 AU at periapsis to 2.2454 AU at apoapsis), the planet experiences minimal orbital distance variation.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 12.600 R⊕, HD 68402 b exceeds the empirical ~1.8–2.2 R⊕ Fulton radius valley threshold, indicating a substantial hydrogen-helium or supercritical volatile envelope without a conventional solid terrestrial surface.
The host star HD 68402 is classified as a solar-type yellow star of spectral type G5 IV/V with an effective photospheric temperature of 5,950 K, a radius of 1.02 R☉, a mass of 1.12 M☉, an estimated bolometric luminosity of 1.17 L☉. Stellar evolution modeling indicates an estimated stellar age of 2 Gyr and a metallicity of [Fe/H] = 0.29 dex (metal-rich relative to the Sun). From Earth, HD 68402 shines at apparent V-band magnitude 9.11 (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 68402 |
| Spectral Type | G5 IV/V |
| Effective Temp (Teff) | 5,950 K |
| Stellar Radius | 1.0200 R☉ |
| Stellar Mass | 1.1200 M☉ |
| Bolometric Luminosity | 1.17 L☉ |
| Metallicity [Fe/H] | 0.290 dex |
| Stellar Age | 2.000 Gyr |
| Apparent Magnitude | V: 9.110 · G: 8.954 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 2.180000 AU |
| Orbital Period | 1103 days |
| Mean Orbital Velocity | 21.5 km/s |
| Orbital Eccentricity (e) | 0.03000 |
| Orbital Inclination (i) | 20.3000° |
| Mean Bulk Density | 6.92 g/cm³ (157.9 km/s vesc) |
| Insolation Flux | 0.2462 S⊕ (~335 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 255.800 LY (78.429 pc) |