55 Cnc B c
Astrophysical Synthesis & Habitability Characterization
55 Cnc B c is a confirmed sub-neptune exoplanet orbiting the star 55 Cnc B, located approximately 40.7 light-years (12.48 parsecs) from the Solar System. First announced in 2025 by Mauna Kea Observatory using the Radial Velocity detection technique (measuring periodic Doppler reflex motion in the host star's spectrum), this world measures 2.16 Earth radii and has a measured mass of 5.3 Earth masses. Combining its mass and radius yields a mean bulk density of 2.9 g/cm³ (an intermediate density indicative of a deep water-ice mantle or dense volatile envelope), a surface gravity of 1.14 g⊕ (11.18 m/s²), and an escape velocity of 17.5 km/s.
In its orbital architecture around 55 Cnc B, 55 Cnc B c completes one full revolution every 33.747 Earth days at a semi-major axis of 0.13 AU (orbiting interior to Mercury's 0.387 AU benchmark in the Solar System). Its mean orbital velocity is approximately 41.9 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 230 K (-43°C / -45°F) and an incident stellar irradiance of 0.46 S⊕ (~628 W/m²), 55 Cnc B c orbits within the empirical circumstellar habitable zone where a rocky surface under sufficient atmospheric pressure can maintain liquid surface water.
The host star 55 Cnc B is classified as a low-mass red dwarf of spectral type M4.5 V with an effective photospheric temperature of 3,286 K, a radius of 0.274 R☉, a mass of 0.26 M☉, an estimated bolometric luminosity of 0.00785 L☉. Stellar evolution modeling indicates an estimated stellar age of 10 Gyr and a metallicity of [Fe/H] = 0.16 dex (metal-rich relative to the Sun). From Earth, 55 Cnc B shines at apparent V-band magnitude 13.152 (faint and requiring research-grade or CCD telescopic photometry) in the Northern celestial hemisphere. The 55 Cnc B system is a multi-planet architecture hosting 2 confirmed worlds, with 55 Cnc B c sharing its stellar neighborhood alongside 55 Cnc B b.
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 | 55 Cnc B |
| Spectral Type | M4.5 V |
| Effective Temp (Teff) | 3,286 K |
| Stellar Radius | 0.2740 R☉ |
| Stellar Mass | 0.2600 M☉ |
| Bolometric Luminosity | 0.00785 L☉ |
| Metallicity [Fe/H] | 0.160 dex |
| Stellar Age | 10.000 Gyr |
| Apparent Magnitude | V: 13.152 · G: 11.680 |
| System Architecture | 2 Stars, 7 Planets |
🪐 Orbital & Physical Dynamics
| Semi-Major Axis (a) | 0.130000 AU |
| Orbital Period | 33.747 days |
| Mean Orbital Velocity | 41.9 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 2.9 g/cm³ (17.5 km/s vesc) |
| Insolation Flux | 0.4613 S⊕ (~628 W/m²) |
| Habitable Zone Status | ★ Temperate Zone |
| Celestial Distance | 40.700 LY (12.477 pc) |