GJ 3021 b
Astrophysical Synthesis & Habitability Characterization
GJ 3021 b is a confirmed gas giant exoplanet orbiting the star GJ 3021, located approximately 57.3 light-years (17.56 parsecs) from the Solar System. First announced in 2000 by La Silla Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 13.1 Earth radii (1.17 Jupiter radii) and has a measured mass of 1071.04 Earth masses (3.37 Jupiter masses). Combining its mass and radius yields a mean bulk density of 2.63 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 6.24 g⊕ (61.19 m/s²), and an escape velocity of 101.1 km/s.
In its orbital architecture around GJ 3021, GJ 3021 b completes one full revolution every 133.71 Earth days at a semi-major axis of 0.49 AU (situated at an orbital separation between Mercury's 0.39 AU and Venus's 0.72 AU). Its mean orbital velocity is approximately 39.9 km/s (compared to Earth's 29.8 km/s). The planet follows a highly eccentric trajectory (e = 0.511, swinging from 0.2396 AU at periapsis out to 0.7404 AU at apoapsis), pointing to past dynamical scattering or secular gravitational perturbations.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 13.100 R⊕, GJ 3021 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 GJ 3021 is classified as a solar-type yellow star of spectral type G6 V with an effective photospheric temperature of 5,540 K, a radius of 0.9 R☉, a mass of 0.9 M☉, an estimated bolometric luminosity of 0.685 L☉. Stellar evolution modeling indicates an estimated stellar age of 0.37 Gyr and a metallicity of [Fe/H] = 0.1 dex (metal-rich relative to the Sun). From Earth, GJ 3021 shines at apparent V-band magnitude 6.59 (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: La Silla Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 3021 |
| Spectral Type | G6 V |
| Effective Temp (Teff) | 5,540 K |
| Stellar Radius | 0.9000 R☉ |
| Stellar Mass | 0.9000 M☉ |
| Bolometric Luminosity | 0.685 L☉ |
| Metallicity [Fe/H] | 0.100 dex |
| Stellar Age | 0.370 Gyr |
| Apparent Magnitude | V: 6.590 · G: 6.397 |
| System Architecture | 2 Stars, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.490000 AU |
| Orbital Period | 133.71 days |
| Mean Orbital Velocity | 39.9 km/s |
| Orbital Eccentricity (e) | 0.51100 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.63 g/cm³ (101.1 km/s vesc) |
| Insolation Flux | 2.7517 S⊕ (~3,745 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 57.300 LY (17.556 pc) |