GJ 3378 b
Astrophysical Synthesis & Habitability Characterization
GJ 3378 b is a confirmed super-earth exoplanet orbiting the star GJ 3378, located approximately 25.2 light-years (7.72 parsecs) from the Solar System. First announced in 2026 by Mauna Kea Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 1.32 Earth radii and has a measured mass of 2.3 Earth masses. Combining its mass and radius yields a mean bulk density of 5.51 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.32 g⊕ (12.94 m/s²), and an escape velocity of 14.8 km/s.
In its orbital architecture around GJ 3378, GJ 3378 b completes one full revolution every 21.45 Earth days at a semi-major axis of 0.09673 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 49.1 km/s (compared to Earth's 29.8 km/s). The orbit is modeled as circular (e = 0.00), maintaining a constant stellar distance throughout its year.
✓ Classified as a Temperate Habitable Zone Candidate.
With an estimated equilibrium temperature of 272 K (-1°C / +30°F) and an incident stellar irradiance of 0.91 S⊕ (~1,239 W/m²), GJ 3378 b orbits within the empirical circumstellar habitable zone where a rocky surface under sufficient atmospheric pressure can maintain liquid surface water.
The host star GJ 3378 is classified as a low-mass red dwarf of spectral type M4 V with an effective photospheric temperature of 3,340 K, a radius of 0.275 R☉, a mass of 0.262 M☉, an estimated bolometric luminosity of 0.00844 L☉. Stellar evolution modeling indicates a metallicity of [Fe/H] = -0.09 dex (near-solar heavy-element abundance). From Earth, GJ 3378 shines at apparent V-band magnitude 12.37 (faint and requiring research-grade or CCD telescopic photometry) 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: Mauna Kea Observatory · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | GJ 3378 |
| Spectral Type | M4 V |
| Effective Temp (Teff) | 3,340 K |
| Stellar Radius | 0.2750 R☉ |
| Stellar Mass | 0.2620 M☉ |
| Bolometric Luminosity | 0.00844 L☉ |
| Metallicity [Fe/H] | -0.090 dex |
| Stellar Age | — |
| Apparent Magnitude | V: 12.370 · G: 10.408 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.096730 AU |
| Orbital Period | 21.45 days |
| Mean Orbital Velocity | 49.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 5.51 g/cm³ (14.8 km/s vesc) |
| Insolation Flux | 0.9100 S⊕ (~1,239 W/m²) |
| Habitable Zone Status | ★ Temperate Zone |
| Celestial Distance | 25.200 LY (7.723 pc) |