| Extrasolar planet | List of extrasolar planets | |
|---|---|---|
The star-like-looking dots around its sun 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 | ||
| Semimajor 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⊕) |
| Discovery information | ||
| Discovery date | 11 April 2005 (announced) 6 November 2007 (published) |
|
| Discoverer(s) | announced by J. Wisdom published by D. Fischer |
|
| Detection method | Doppler spectroscopy | |
| Discovery site | United States | |
| Discovery status | Published | |
| Other designations | ||
|
55 Cancri Af, Rho1 Cancri f, HD 75732 f
|
||
| Database references | ||
| Extrasolar Planets Encyclopaedia |
data | |
| SIMBAD | data | |
55 Cancri f (abbreviated 55 Cnc f and also referred to as Rho1 Cancri f) 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]
Contents |
The initial presentation of this planet occurred at a meeting of the American Astronomical Society in April 2005,[3] 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".[4] Furthermore, its discovery made 55 Cancri the first star other than the Sun known to have at least five planets.
55 Cancri f is located about 0.781 AU away from the star and takes 260 days to complete a full orbit.[5] 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.[5] 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.[6] If these measurements are confirmed and the system is assumed to be coplanar, the true mass of 55 Cancri f would therefore be about 25% greater than this lower limit, at around 0.18 Jupiter masses.[1]
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,[5] 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.[4]
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.
| Book: 55 Cancri | |
| Wikipedia books are collections of articles that can be downloaded or ordered in print. | |
|
||||||||||||||
Coordinates: 08h 52m 35.8s, +28° 19′ 51″
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||