Gliese 48 b
Astrophysical Synthesis & Habitability Characterization
Gliese 48 b is a confirmed sub-neptune exoplanet orbiting the star Gliese 48, located approximately 26.9 light-years (8.23 parsecs) from the Solar System. First announced in 2026 by Multiple Observatories using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.77 Earth radii and has a measured mass of 8.11 Earth masses. Combining its mass and radius yields a mean bulk density of 2.1 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.06 g⊕ (10.4 m/s²), and an escape velocity of 19.1 km/s.
In its orbital architecture around Gliese 48, Gliese 48 b completes one full revolution every 39.63 Earth days at a semi-major axis of 0.1752 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 48.1 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.
☁️ Atmospheric Regime (Volatile / Gas Envelope): With a radius of 2.770 R⊕, Gliese 48 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 Gliese 48 is classified as a low-mass red dwarf of spectral type M3.5 V with an effective photospheric temperature of 3,450 K, a radius of 0.463 R☉, a mass of 0.47 M☉, an estimated bolometric luminosity of 0.027 L☉. From Earth, Gliese 48 shines at apparent V-band magnitude 9.98 (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: Multiple Observatories · Catalogue Source: NASA Exoplanet Archive (IPAC / Caltech).
☀️ Host Star Telemetry
| Host Star Name | Gliese 48 |
| Spectral Type | M3.5 V |
| Effective Temp (Teff) | 3,450 K |
| Stellar Radius | 0.4630 R☉ |
| Stellar Mass | 0.4700 M☉ |
| Bolometric Luminosity | 0.027 L☉ |
| Metallicity [Fe/H] | — |
| Stellar Age | — |
| Apparent Magnitude | V: 9.980 · G: 8.933 |
| System Architecture | 1 Star, 1 Planet |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.175200 AU |
| Orbital Period | 39.63 days |
| Mean Orbital Velocity | 48.1 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | 89.3000° |
| Mean Bulk Density | 2.1 g/cm³ (19.1 km/s vesc) |
| Insolation Flux | 0.8900 S⊕ (~1,211 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 26.900 LY (8.234 pc) |