Space Codex / Exoplanet reference
Published exoplanet measurements
55 Cnc e
55 Cnc e orbits 55 Cnc once every 0.736547 days. The system is about 41.0484 light-years from Earth.
Archive retrieved November 1, 2026 (America/New_York). The selected paper and archive update dates appear below.
The recorded orbit
The selected archive solution gives an orbital period of 0.736547 days, or 0.00201656 Earth years. Its reported semimajor axis is 0.01544 AU. That orbital scale is 0.0398865 times Mercury's semimajor axis. The listed eccentricity is 0.05. Using those central values, the model's nearest and farthest star–planet distances are about 0.014668 and 0.016212 AU. These are derived comparisons, without propagated errors. The period measures a year on this planet. It does not establish the length of its rotation or the duration of daylight.
Read how orbital period, size, and eccentricity fit together.
Size and mass
The radius parameter is 1.875 (+0.029 / −0.029) Earth radii. Radius describes size; it does not specify the mass or the atmospheric composition. The mass parameter is 7.99 (+0.32 / −0.33) Earth masses. Its archive provenance is Mass. The source lists a bulk-density parameter of 6.66 (+0.43 / −0.4) g/cm³. Different interior mixtures can overlap in density; the value does not identify a unique surface.
The host star and received light
The host is cataloged as 55 Cnc. Its reported effective temperature is 5172 K. Its reported radius is 0.943 solar radii. Its reported mass is 0.905 solar masses. The available stellar and orbital entries do not establish a breathable atmosphere, surface water, or life.
What a habitable-zone claim does and does not mean · How a star changes over time.
Other planets around 55 Cnc
The fetched archive contains 5 selected default planet records for this host. This is the retrieved record set, and additional or revised discoveries may appear in later research.
| Planet | Period (days) | Radius (Earth) | Mass parameter (Earth) | Mass definition |
|---|---|---|---|---|
| 55 Cnc e | 0.736547 (+1.3e-06 / −1.4e-06) | 1.875 (+0.029 / −0.029) | 7.99 (+0.32 / −0.33) | Mass |
| 55 Cnc b | 14.6516 (+3.6e-05 / −3.6e-05) | Not reported in this solution | 276 (+9 / −9) | Msini |
| 55 Cnc c | 44.3936 (+0.0024 / −0.0024) | Not reported in this solution | 56.6 (+2.2 / −2.2) | Msini |
| 55 Cnc f | 260.58 (+0.15 / −0.15) | Not reported in this solution | 48.5 (+2.8 / −2.8) | Msini |
| 55 Cnc d | 4799 (+4.9 / −15) | Not reported in this solution | 1214.1 (+41.3177 / −41.3177) | Msini |
Earth comparison
| Quantity | Reported value or conversion | Comparison |
|---|---|---|
| Orbital period | 0.736547 days | 0.00201656 Earth years |
| System distance | 12.5855 parsecs | 41.0484 light-years |
| Orbital scale | 0.01544 (+5e-05 / −5e-05) | AU; Earth = 1 |
| Radius | 1.875 (+0.029 / −0.029) | Earth radii; Earth = 1 |
| Mass parameter | 7.99 (+0.32 / −0.33) | Earth masses; check mass definition |
Conversions use rounded central values. They are navigation aids for the data, not additional observations. Uncertainties for the original parameters remain in the next table.
Measurement table
| Parameter | Value and reported uncertainty | Unit or definition |
|---|---|---|
| Orbital period | 0.736547 (+1.3e-06 / −1.4e-06) | days |
| Semimajor axis | 0.01544 (+5e-05 / −5e-05) | AU |
| Radius | 1.875 (+0.029 / −0.029) | Earth radii |
| Mass parameter | 7.99 (+0.32 / −0.33) | Earth masses |
| Orbital eccentricity | 0.05 (+0.03 / −0.03) | dimensionless |
| Orbital inclination | 83.59 (+0.47 / −0.44) | degrees |
| Equilibrium temperature | Not reported in this solution | K; model estimate |
| Incident flux | Not reported in this solution | Earth flux |
| Bulk density | 6.66 (+0.43 / −0.4) | g/cm³ |
| Host effective temperature | 5172 (+18 / −18) | K |
| Host radius | 0.943 (+0.01 / −0.01) | solar radii |
| Host mass | 0.905 (+0.015 / −0.015) | solar masses |
| Host metallicity | 0.35 (+0.1 / −0.1) | dex; archive abundance definition |
| Host age | Not reported in this solution | billion years |
| Host luminosity | Not reported in this solution | log10 solar luminosity |
| Host surface gravity | 4.43 (+0.02 / −0.02) | log10 cm/s² |
| Host rotation period | 38.8 | days |
| System distance | 12.5855 (+0.0124 / −0.0123) | parsecs |
Parentheses show the reported upper and lower uncertainties when both are supplied. Bounds are explicitly labeled. A missing entry means unavailable in this solution, not zero. The confidence convention belongs to the source paper.
Research record and limitations
| Record | Value |
|---|---|
| Planetary reference | Bourrier et al. 2018 |
| Discovery method | Radial Velocity |
| Discovery year | 2004 |
| Discovery facility | McDonald Observatory |
| Mass provenance | Mass |
| Host stars in system | 2 |
| Archive system planet count | 7 |
| Planetary solution publication date | 2018-10 |
| Row update date | 2021-02-05 |
| Archive release date | 2021-02-11 |
Source: NASA Exoplanet Archive overview for 55 Cnc e, Planetary Systems table, default solution. The collection excludes entries flagged controversial at retrieval. A selected default is a published reference choice, not a claim that every parameter is the latest estimate in all literature.
This profile documents measurements and their scope. It is separate from the 3D planet catalog and does not create a sponsorship placement or a new explorer destination.