55 Cancri f
| Exoplanet | List of exoplanets | |
|---|---|---|
 The three bright dots near its star are the three innermost planets. | ||
| Parent star | ||
| Star | 55 Cancri A | |
| Constellation | Cancer | |
| Right ascension | (α) | 08h 52m 35.8s |
| Declination | (δ) | +28° 19′ 51″ |
| Apparent magnitude | (mV) | 5.95 |
| Distance | 40.3 ± 0.4 ly (12.3 ± 0.1 pc) | |
| Spectral type | G8V | |
| Mass | (m) | 0.95 ± 0.10 M☉ |
| Radius | (r) | 1.152 ± 0.035 R☉ |
| Temperature | (T) | 5373 ± 9.7 K |
| Metallicity | [Fe/H] | 0.29 |
| Age | 7.4–8.7 Gyr | |
| Orbital elements | ||
| Semi-major axis | (a) | 0.781 ± 0.007[1] AU (116.9 Gm) |
| 62.5 mas | ||
| Periastron | (q) | 0.730 AU (109.1 Gm) |
| Apastron | (Q) | 0.833 AU (124.6 Gm) |
| Eccentricity | (e) | 0.2 ± 0.2[1] |
| Orbital period | (P) | 260.00 ± 1.1[1] d (0.7118 y) |
| Argument of periastron |
(ω) | 181.1 ± 60[1]° |
| Time of periastron | (T0) | 2,450,080.9108 ± 1.1[1] JD |
| Semi-amplitude | (K) | 4.879 ± 0.6[1] m/s |
| Physical characteristics | ||
| Minimum mass | (m sin i) | 0.144 ± 0.04[1] MJ (45.7 ± 12.7[1] M⊕) |
| Stellar flux | (F⊙) | ~1 ⊕ |
| Temperature | (T) | 200–300 K (−73–27 °C; −100–80 °F) |
| Discovery information | ||
| Discovery date | 11 April 2005 (announced) 6 November 2007 (published) | |
| Discoverer(s) | announced by J. Wisdom published by D. Fischer | |
| Discovery method | Doppler spectroscopy | |
| Discovery site |  United States | |
| Discovery status | Published | |
| Other designations | ||
| Harriot, 55 Cancri Af, Rho1 Cancri f, HD 75732 f | ||
| Database references | ||
| Extrasolar Planets Encyclopaedia | data | |
| SIMBAD | data | |
| Exoplanet Archive | data | |
| Open Exoplanet Catalogue | data | |
55 Cancri f (abbreviated 55 Cnc f), also designated Rho1 Cancri f and named Harriot, is an extrasolar planet approximately 41 light-years away from Earth in the constellation of Cancer (the Crab). 55 Cancri f is the fourth known planet (in order of distance) from the star 55 Cancri and the first planet to have been given the designation of "f".[2]
In July 2014 the International Astronomical Union launched a process for giving proper names to certain exoplanets and their host stars.[3] The process involved public nomination and voting for the new names.[4] In December 2015, the IAU announced the winning name was Harriot for this planet.[5] The winning name was submitted by the Royal Netherlands Association for Meteorology and Astronomy of the Netherlands. It honors the astronomer Thomas Harriot.[6]
Discovery
The initial presentation of this planet occurred at a meeting of the American Astronomical Society in April 2005,[7] 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 our solar system to spend its entire orbit within what astronomers call the "habitable zone".[8] Furthermore, its discovery made 55 Cancri the first star other than the Sun known to have at least five planets.
Orbit and mass
55 Cancri f is located about 0.781 AU away from the star and takes 260 days to complete a full orbit.[9] A limitation of the radial velocity method used to detect 55 Cancri f is that only a minimum mass can be obtained, in this case around 0.144 times that of Jupiter, or half the mass of Saturn.[9] A Keplerian 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 the chi-squared statistic of the fit, thus a representative eccentricity of 0.2±0.2 was assumed.[1] In a Newtonian model which takes interactions between the planets into account, the eccentricity comes out as 0.0002, almost perfectly circular.[1]
Astrometric observations made with the Hubble Space Telescope suggest that the outer planet 55 Cancri d is inclined at 53° with respect to the plane of the sky.[10] The inner planets b and e are inclined at 85°. The inclination of f is unknown.
Characteristics
Since the planet was detected indirectly through observations of its star, properties such as its radius, composition and temperature are unknown. With a mass half that of Saturn,[9] 55 Cancri f is likely to be a gas giant with no solid surface. It orbits in the so-called "habitable zone," which means that liquid water could exist on the surface of a possible moon.[8]
It is not known if the composition and appearance is more like Saturn or Neptune.[2] Based on its temperature, it should be a Sudarsky Class II planet, covered in water clouds.
References
- 1 2 3 4 5 6 7 8 9 10 11 Debra A. Fischer; Geoffrey W. Marcy; R. Paul Butler; Steven S. Vogt; Greg Laughlin; Gregory W. Henry; et al. (23 December 2007). "Five Planets Orbiting 55 Cancri". Astrophysical Journal. 675: 790–801. arXiv:0712.3917
. Bibcode:2008ApJ...675..790F. doi:10.1086/525512. - 1 2 Shige Abe (12 November 2007). "Researchers Identify First Five-Planet Extrasolar System". NASA Astrobiology. Archived from the original on 16 September 2008. Retrieved 17 September 2008.
- ↑ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
- ↑ NameExoWorlds The Process
- ↑ Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
- ↑ NameExoWorlds The Approved Names
- ↑ J. Wisdom (11 April 2005). "A Neptune-sized Planet in the rho1 Cancri System". DDA 36th Meeting, 10–14 April 2005—Session 5 Posters. The American Astronomical Society. Archived from the original on 16 December 2006. Retrieved 17 September 2008.
- 1 2 Ian Sample, science correspondent (7 November 2007). "Could this be Earth's near twin? Introducing planet 55 Cancri f". London: The Guardian. Archived from the original on 2 October 2008. Retrieved 17 October 2008.
- 1 2 3 Jean Schneider (2011). "Notes for Planet 55 Cnc f". Extrasolar Planets Encyclopaedia. Retrieved 8 October 2011.
- ↑ Han; et al. (2001). "Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions". The Astrophysical Journal Letters. 548 (1): L57–L60. Bibcode:2001ApJ...548L..57H. doi:10.1086/318927.
External links
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Wikimedia Commons has media related to 55 Cancri f. |
- Ward Glen (8 November 2007). "Astronomers Find Fifth Planet Around 55 Cancri". The Starry Mirror. Retrieved 17 September 2008.
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Coordinates: 
08h 52m 35.8s, +28° 19′ 51″