55 Cnc B b
Astrophysical Synthesis & Habitability Characterization
55 Cnc B b is a confirmed super-earth 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 1.69 Earth radii and has a measured mass of 3.5 Earth masses. Combining its mass and radius yields a mean bulk density of 4 g/cm³ (a terrestrial silicate-iron composition comparable to Earth (5.51 g/cm³)), a surface gravity of 1.23 g⊕ (12.06 m/s²), and an escape velocity of 16.1 km/s.
In its orbital architecture around 55 Cnc B, 55 Cnc B b completes one full revolution every 6.799 Earth days at a semi-major axis of 0.044 AU (an ultra-close orbit less than one-seventh of Mercury's 0.387 AU distance from the Sun, where strong stellar tidal forces typically induce synchronous rotation). Its mean orbital velocity is approximately 70.4 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.
⚠️ Thermal Regime (Irradiated / Hot Zone): At an equilibrium temperature of 395 K (+122°C / +252°F) and receiving 4.03 S⊕ (~5,481 W/m²), 55 Cnc B b orbits interior to the runaway greenhouse boundary where surface liquid water cannot persist.
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 b sharing its stellar neighborhood alongside 55 Cnc B c.
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) | 0.044000 AU |
| Orbital Period | 6.799 days |
| Mean Orbital Velocity | 70.4 km/s |
| Orbital Eccentricity (e) | 0.00000 |
| Orbital Inclination (i) | — |
| Mean Bulk Density | 4 g/cm³ (16.1 km/s vesc) |
| Insolation Flux | 4.0271 S⊕ (~5,481 W/m²) |
| Habitable Zone Status | Exterior / Non-HZ |
| Celestial Distance | 40.700 LY (12.477 pc) |