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| 55 Cancri | |
|---|---|
| Name | 55 Cancri |
| Other names | Rho1 Cancri, Copernicus |
| Constellation | Cancer |
| Epoch | J2000 |
| Type | G-type main-sequence star |
| Apparent magnitude | 5.95 |
| Distance | 41 ly |
| Mass | 0.95 M☉ |
| Radius | 0.96 R☉ |
| Temperature | 5250 K |
| Metallicity | [Fe/H] ≈ +0.3 |
55 Cancri is a Sun-like G-type main-sequence star located in the constellation Cancer. It is notable for hosting a multi-planet system with a variety of exoplanets including a transiting super-Earth and gas giants, and for being relatively nearby within the local stellar neighborhood. The system has been the focus of studies by observatories and missions such as Palomar Observatory, Keck Observatory, Hubble Space Telescope, Spitzer Space Telescope, and Gaia (spacecraft).
55 Cancri sits near the ecliptic in Cancer and is visible to the unaided eye under dark skies. The star has historic catalog entries in compilations like the Henry Draper Catalogue, Hipparcos Catalogue, and Gliese Catalogue of Nearby Stars. As one of the earlier multiplanet host stars identified by radial velocity surveys, it has been central to the development of techniques used at institutions including University of California, Berkeley, California Institute of Technology, Carnegie Institution for Science, and Harvard–Smithsonian Center for Astrophysics.
The star is classified as a G-type main-sequence star in surveys such as the Morgan–Keenan spectral classification and appears in spectral atlases maintained by facilities like European Southern Observatory and Cerro Tololo Inter-American Observatory. Its effective temperature, metallicity, mass, and radius have been measured using techniques refined at Mount Wilson Observatory, Palomar Observatory, and instruments like the High Resolution Echelle Spectrometer and the High Accuracy Radial velocity Planet Searcher. Parallax measurements from Hipparcos and refined by Gaia (spacecraft) place it at about 41 light-years, making it part of the local sample studied by programs including the Nearby Stars (NStars) project and the RECONS team. Stellar activity and rotation have been characterized using chromospheric indices from long-term programs at Lowell Observatory and photometric monitoring campaigns with telescopes such as Robo-AO and networks like the American Association of Variable Star Observers.
The planetary system contains multiple planets detected primarily via radial velocity methods pioneered by teams at Lick Observatory, Keck Observatory, and the Anglo-Australian Observatory. Confirmed planets include a hot Jupiter-type gas giant discovered in radial velocity surveys, a long-period Jovian companion analogous to those found in surveys by Geneva Observatory teams, and a transiting super-Earth whose transit was observed with space telescopes like Spitzer Space Telescope and ground-based follow-up coordinated by groups at University of Cambridge and University of Geneva. Studies of orbital dynamics and stability have involved collaborations among researchers at Massachusetts Institute of Technology, Princeton University, University of California, Santa Cruz, and University of Texas at Austin, employing n-body integrators originally developed in computational astrophysics groups at NASA Ames Research Center and Jet Propulsion Laboratory. The architecture has been compared to other multiplanet hosts such as Upsilon Andromedae, HD 10180, Kepler-11, Trappist-1, and Gliese 876.
Investigations of potential habitability reference habitable zone estimates derived using models from researchers associated with University of Arizona, Pennsylvania State University, and University of Washington. Analyses have considered the influence of giant planets on orbital stability of hypothetical terrestrial worlds, drawing on methodologies used in studies of Solar System dynamics, Jupiter-Saturn interactions, and secular perturbation theory developed by scholars at Princeton University and Cornell University. Observations with infrared facilities such as Spitzer Space Telescope and submillimeter arrays including Atacama Large Millimeter/submillimeter Array searched for circumstellar dust or debris disks analogous to the Kuiper belt or Asteroid belt, in a manner similar to surveys by Herschel Space Observatory. Results constrain the presence of warm debris and inform comparisons with systems like Fomalhaut and Beta Pictoris.
Radial velocity variations were first reported by teams using spectrographs at Lick Observatory and later confirmed and refined by surveys at Keck Observatory and the Anglo-Australian Telescope. The transiting planet detection leveraged time-series photometry techniques developed at Spitzer Science Center and analysis pipelines from groups affiliated with California Institute of Technology and NASA Exoplanet Science Institute. Long-term monitoring campaigns have involved observatories such as Mount Wilson Observatory, Fairborn Observatory, and networks like the Whole Earth Telescope, with data incorporated into catalogs maintained by SIMBAD and the NASA Exoplanet Archive. The system’s nomenclature and planet confirmations were discussed at international meetings including the American Astronomical Society conferences and publications in journals like The Astrophysical Journal and Astronomy & Astrophysics.
The star received a proper name in the International Astronomical Union naming campaigns and is also known by historic names cataloged in the Bayer designation and other catalogs. Its planets inspired public interest through media outlets like Nature (journal), Science (journal), BBC, and National Geographic, and featured in science communication by organizations including SETI Institute, Planetary Society, and European Space Agency. The system has appeared in science fiction treatments in works associated with publishers such as Tor Books and discussions in outreach programs at institutions like Smithsonian Institution and American Museum of Natural History.
Category:Stars Category:Exoplanet host stars