 An artist's impression of 55 Cancri f. The three bright dots near its star are the three innermost planets. | |
| Discovery | |
|---|---|
| Discovered by | announced by J. Wisdom published by D. Fischer |
| Discovery site | United States |
| Discovery date | 11 April 2005 (announced) 6 November 2007 (published) |
| Doppler spectroscopy | |
| Orbital characteristics | |
| Apastron | 0.833 AU (124,600,000 km) |
| Periastron | 0.730 AU (109,200,000 km) |
| 0.781 ± 0.007 AU (116,800,000 ± 1,000,000 km)[1] | |
| Eccentricity | 0.2 ± 0.2[1] |
| 260.00 ± 1.1[1]d 0.7118y | |
| 2,450,080.9108 ± 1.1[1] | |
| 181.1 ± 60[1] | |
| Semi-amplitude | 4.879 ± 0.6[1] |
| Star | 55 Cancri A |
| Physical characteristics | |
| Temperature | 200–300 K (−73–27 °C; −100–80 °F) |
55 Cancri f (abbreviated55 Cnc f), also designatedRho1 Cancri f and formally namedHarriot/ˈhæriət/,[2] is anexoplanet approximately 41light-years away from Earth in theconstellation ofCancer (theCrab). 55 Cancri f is the fourth known planet (in order of distance) from the star55 Cancri and the first planet to have been given the designation of "f".[3]
In July 2014 theInternational Astronomical Union launchedNameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.[4] The process involved public nomination and voting for the new names.[5] In December 2015, the IAU announced the winning name was Harriot for this planet.[6] The winning name was submitted by the Royal Netherlands Association for Meteorology and Astronomy of theNetherlands. It honors the astronomerThomas Harriot.[7]
The initial presentation of this planet occurred at a meeting of theAmerican Astronomical Society in April 2005,[8] however it was another two and a half years before the planet was to be published in a peer-reviewed journal.[1] It is the first known planet outside the Solar System to spend its entire orbit within what astronomers call the "habitable zone".[9] Furthermore, its discovery made55 Cancri the first star other than theSun known to have at least five planets.
55 Cancri f is located about 0.781AU away from the star and takes 262 days to complete a full orbit.[10] A limitation of the radial velocity method used to detect 55 Cancri f is that only aminimum mass can be obtained, in this case around 0.144 times that of Jupiter, or half the mass ofSaturn.[10] AKeplerian fit to the radial velocity data of 55 Cancri A indicates that the orbit is consistent with being circular, however changing the value in a range between 0 and 0.4 does not significantly alter thechi-squared statistic of the fit, thus a representative eccentricity of 0.2±0.2 was assumed.[1] In aNewtonian model which takes interactions between the planets into account, the eccentricity comes out as 0.0002, almost perfectly circular.[1]
Astrometric observations made with theHubble Space Telescope suggest that the outer planet55 Cancri d is inclined at 53° with respect to the plane of the sky.[11] The inner planets b and e are inclined at 85°. The inclination of f is unknown.
Since the planet was detected indirectly through observations of its star, properties such as itsradius, composition andtemperature are unknown. With a mass half that ofSaturn,[10] 55 Cancri f is likely to be agas giant with no solid surface. It orbits in the so-called "habitable zone," which means thatliquid water andlife could exist on the surface of a possible moon.[9]
It is also possible that 55 Cancri f is a "temperate ice giant" orhycean planet due to its orbit and possible hydrogen-rich composition.
It is not known if the composition and appearance is more like that of Saturn or Neptune.[3]
Media related to55 Cancri f at Wikimedia Commons
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