55 Cancri
![Sky map](http://upload.wikimedia.org/wikipedia/commons/thumb/e/e4/Jupiter_and_moon.png/20px-Jupiter_and_moon.png)
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Cancer |
Pronunciation
|
/ˈkæŋkraɪ/ or /ˈkæŋkriː/ |
55 Cancri A | |
Right ascension | 08h 52m 35.8111s[1] |
Declination | +28° 19′ 50.955″[1] |
Apparent magnitude (V) | 5.95[2] |
55 Cancri B | |
Right ascension | 08h 52m 40.8627s[3] |
Declination | +28° 19′ 58.821″[3] |
Apparent magnitude (V) | 13.15[4] |
Characteristics | |
55 Cancri A | |
Evolutionary stage | Main sequence or subgiant |
Spectral type | K0IV–V[5] |
U−B color index | 0.63[6] |
B−V color index | 0.87[6] |
55 Cancri B | |
Evolutionary stage | Main sequence (red dwarf) |
Spectral type | M4.5V[7] |
B−V color index | 1.7[4] |
Absolute magnitude (MV) | +12.58±0.088[9] |
Details | |
55 Cnc A | |
Rotational velocity (v sin i) | 2.36[9] km/s |
HR 3522, SAO 80585 | |
Database references | |
Exoplanet Archive | data |
ARICNS | data |
55 Cancri is a
As of 2015[update], five
Nomenclature
55 Cancri is the system's Flamsteed designation. It also bears the Bayer designation ρ1 Cancri (Latinised to Rho1 Cancri) and the Bright Star Catalogue designation HR 3522. The two components are designated A and B,[14] though component A is sometimes referred to simply as 55 Cancri.[15] The first planet discovered orbiting 55 Cancri A was designated HR 3522b by its discoverers,[16] though it is more commonly referred to as 55 Cancri b.[17] Under the rules for naming objects in binary star systems it should be named 55 Cancri Ab[18] and this more formal form is occasionally used to avoid confusion with the secondary star 55 Cancri B. The other planets discovered were designated 55 Cancri c, d, e and f, in order of their discovery.
In July 2014 the International Astronomical Union launched NameExoWorlds, a process for giving proper names to certain exoplanets and their host stars.[19] The process involved public nomination and voting for the new names.[20] In December 2015, the IAU announced the winning names were Copernicus for 55 Cancri A and Galileo, Brahe, Lipperhey, Janssen and Harriot for its planets (b, c, d, e and f, respectively).[21]
The winning names were those submitted by the Royal Netherlands Association for Meteorology and Astronomy of the
In 2016, the IAU organized a
Stellar system
The 55 Cancri system is located fairly close to the
55 Cancri A
The primary star, 55 Cancri A, has a
A hypothesis for the high metal content in SMR dwarf stars is that material enriched in heavy elements fell into the atmosphere from a protoplanetary disk. This would pollute the star's external layers, resulting in a higher than normal metallicity. The lack of a deep convection zone would mean that the outer layers would retain higher abundance ratios of these heavy elements.[29]
Observations of 55 Cancri A in the submillimeter region of the spectrum have thus far failed to detect any associated dust. The upper limit on emissions within 100 AU of this star is about 850 mJy, at a wavelength of 850 μm. This limits the total mass of fine dust around the star to less than 0.01% of the Earth's mass. However, this does not exclude the presence of an asteroid belt or a Kuiper belt equivalent.[30]
55 Cancri B
The secondary, 55 Cancri B, is a red dwarf star much less massive and luminous than the Sun. There are indications that component B may itself be a double star, though this is uncertain.[14]
Planetary system
Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
---|---|---|---|---|---|---|
e (Janssen) | 7.99+0.32 −0.33 M🜨 |
0.01544 ± 0.00005 | 0.73654625±0.00000015[33] | 0.05 ± 0.03 | 83.59+0.47 −0.44° |
1.875 ± 0.029 R🜨 |
b (Galileo) | ≥0.8036+0.0092 −0.0091 MJ |
0.1134 ± 0.0006 | 14.6516 ± 0.0001 | 0 ± 0.01 | ~85° | — |
c (Brahe) | ≥51.2 ± 1.3 M🜨 | 0.2373 ± 0.0013 | 44.3989+0.0042 −0.0043 |
0.03 ± 0.02 | — | — |
f (Harriot) | ≥47.8 ± 2.4 M🜨 | 0.7708+0.0043 −0.0044 |
259.88 ± 0.29 | 0.08+0.05 −0.04 |
— | — |
d (Lipperhey) | ≥3.12 ± 0.10 MJ | 5.957+0.074 −0.071 |
5,574.2+93.8 −88.6 |
0.13 ± 0.02 | — | — |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/8/85/55CncInnerOrbits.svg/220px-55CncInnerOrbits.svg.png)
The 55 Cancri system was the first known to have four, and later five, planets, and may possibly have more. The innermost planet, e,
In 1997, the discovery of a
In 1998 the discovery of a possible dust disk around 55 Cancri A was announced.[34] Calculations gave the disk radius at least 40 AU, similar to the Kuiper belt in the Solar System, with an inclination of 25° with respect to the plane of the sky. However, the discovery could not be verified and was later deemed to be spurious, caused instead by background galaxies.[35]
![](http://upload.wikimedia.org/wikipedia/commons/thumb/5/59/Extrasolar_planet_NASA2.jpg/220px-Extrasolar_planet_NASA2.jpg)
After making further radial velocity measurements, a planet orbiting at a distance of around 5 AU was announced in 2002.[15] This planet received the designation 55 Cancri d. At the time of discovery, the planet was thought to be in an orbit of mild eccentricity (close to 0.1), but this value was increased by later measurements. Even after accounting for these two planets, a periodicity at 43 days remained, possibly due to a third planet. Measurements of the star suggested that this was close to the star's rotation period, which raised the possibility that the 43-day signal was caused by stellar activity. This possible planet received the designation 55 Cancri c.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/6d/55Cnc_system.jpg/220px-55Cnc_system.jpg)
In 2005, Jack Wisdom combined three data sets and drew two distinct conclusions: that the 2.8-day planet was an alias and that there was a Neptune-scale planet with a period near 261 days. Fischer et al. (2008)[37] reported new observations that they said confirmed the existence of the 2.8-day planet, as first reported by McArthur et al. (2004), and a 260-day Neptune-sized planet, as first reported by Wisdom (2005).[38] However, Dawson and Fabrycky (2010)[32] concluded that the 2.8-day planet was indeed an alias, as suggested by Wisdom (2005), and that the correct period was 0.7365 of a day.
In 2007, Fisher et al. confirmed the existence of the 260-day planet proposed in 2005 by Wisdom. This planet, 55 Cancri f, was the first occurrence of a fifth extrasolar planet in one system. With a similar mass to c, it has a 260-day orbit, towards the inner edge of 55 Cancri A's habitable zone.[39][40] The planet itself is not thought to be conducive to life, but hypothetical moons in principle could maintain at least water and life.
The planet e's eccentricity is poorly defined; varying values between 0 and 0.4 does not significantly improve the fit, so an eccentricity of 0.2 was assumed. Taking interactions between the planets into account results in a near-zero orbital eccentricity.
Astrometric observations with the
The approximate ratios of periods of adjacent orbits are (proceeding outward): 1:20, 1:3, 1:6, 1:20. The nearly 1:3 ratio between 55 Cancri b and c is apparently a
Possible additional planets
Between planets f and d, there appears to be a huge gap of distance where no planets are known to orbit. A 2008 paper found that as many as 3 additional planets of up to 50 times the mass of Earth could orbit at a distance of 0.9 to 3.8 AU from the star, and stable resonances of a hypothetical planet g with the known planets were found to be 3f:2g, 2g:1d, and 3g:2d.
Communication
A
See also
- Sudarsky's gas giant classification
- Cancer in Chinese astronomy
- Kepler-186
- Lists of exoplanets
- Gliese 1132 b– rocky exoplanet with a confirmed atmosphere
- Mu Arae c – At constellation Ara
- Planetary system
- PSR B1257+12
References
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- ^ S2CID 119118088.
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- ^ S2CID 209888143.
- ^ S2CID 102351979. A68.
- ^ a b "IAU Catalog of Star Names". Retrieved 28 July 2016.
- ^ S2CID 5669768.
- ^ S2CID 16170184.
- ^ S2CID 124194712.
- ^ Jean Schneider (2011). "Notes for Planet 55 Cnc b". Extrasolar Planets Encyclopaedia. Retrieved 8 October 2011.
- ^ William I. Hartkopf & Brian D. Mason. "Addressing confusion in double star nomenclature: The Washington Multiplicity Catalog". United States Naval Observatory. Archived from the original on 2011-05-17. Retrieved 2011-10-08.
- ^ NameExoWorlds: An IAU Worldwide Contest to Name Exoplanets and their Host Stars. IAU.org. 9 July 2014
- ^ "NameExoWorlds The Process". Archived from the original on 2015-08-15. Retrieved 2015-09-05.
- ^ a b Final Results of NameExoWorlds Public Vote Released, International Astronomical Union, 15 December 2015.
- ^ a b "NameExoWorlds The Approved Names". Archived from the original on 2018-02-01. Retrieved 2015-12-27.
- ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
- ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
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- ^ ISSN 0004-6361.
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- ^ Pasquini, Luca; Hatzes, Artie (2007-07-06). "Star Surface Polluted by Planetary Debris". ESO. Archived from the original on 30 September 2007. Retrieved 2007-11-08.
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- ^ S2CID 119085463.
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- Bibcode:2005DDA....36.0508W.
- ^ "Astronomers Discover Record Fifth Planet Around Nearby Star 55 Cancri". Sciencedaily.com. November 6, 2007. Archived from the original on 26 September 2008. Retrieved 2008-09-14.
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- ^ "Передача и поиски разумных сигналов во Вселенной" (PDF). Cplire.ru. Archived from the original on 2019-05-30. Retrieved 2008-09-14.
Further reading
- Ji, Jianghui; Kinoshita, Hiroshi; Liu, Lin; Li, Guangyu (2003). "Could the 55 Cancri Planetary System Really Be in the 3[rcolon]1 Mean Motion Resonance?". The Astrophysical Journal. 585 (2): L139–L142. S2CID 15993774.
- Schneider, G.; Becklin, E. E.; Smith, B. A.; Weinberger, A. J.; Silverstone, M.; Hines, D. C. (2001). "NICMOS Coronagraphic Observations of 55 Cancri". The Astronomical Journal. 121 (1): 525–537. S2CID 14503540.
- Jayawardhana, Ray; Holland, Wayne S.; Kalas, Paul; Greaves, Jane S.; Dent, William R. F.; Wyatt, Mark C.; Marcy, Geoffrey W. (2002). "New Submillimeter Limits on Dust in the 55 Cancri Planetary System". The Astrophysical Journal. 570 (2): L93–L96. S2CID 15516278.
- Zhou, Li-Yong; J. Lehto, Harry; Sun, Yi-Sui; Zheng, Jia-Qing (2004). "Apsidal corotation in mean motion resonance: the 55 Cancri system as an example". S2CID 16821093.
- Jayawardhana, Ray; Holland, Wayne S.; Greaves, Jane S.; Dent, William R. F.; Marcy, Geoffrey W.; Hartmann, Lee W.; Fazio, Giovanni G. (2000). "Dust in the 55 Cancri Planetary System". The Astrophysical Journal. 536 (1): 425–428. S2CID 44777812.
- Rasio, F. A.; Ford, E. B. (1996). "Dynamical Instabilities and the Formation of Extrasolar Planetary Systems". Science. 274 (5289): 954–956. S2CID 2940958.
- von Bloh, W.; Cuntz, M.; Franck, S.; Bounama, C. (2003). "On the Possibility of Earth-Type Habitable Planets in the 55 Cancri System". Astrobiology. 3 (4): 681–688. PMID 14987474.
- Ji, Jiang-Hui; Kinoshita, Hiroshi; Liu, Lin; Li, Guang-Yu (2009). "The dynamical architecture and habitable zones of the quintuplet planetary system 55 Cancri". Research in Astronomy and Astrophysics. 9 (6): 703–711. S2CID 15304622.
- Raymond, Sean N.; Barnes, Rory; Gorelick, Noel (2008). "A Dynamical Perspective on Additional Planets in 55 Cancri". The Astrophysical Journal. 689 (1): 478–491. S2CID 941288.
- Marzari, F.; Scholl, H.; Tricarico, P. (2005). "Frequency map analysis of the 3/1 resonance between planets b and c in the 55 Cancri system" (PDF). Astronomy and Astrophysics. 442 (1): 359–364. ISSN 0004-6361.
External links
![](http://upload.wikimedia.org/wikipedia/en/thumb/4/4a/Commons-logo.svg/30px-Commons-logo.svg.png)
- "55 (Rho1) Cancri 2". SolStation. Archived from the original on 25 June 2008. Retrieved 2008-06-12.
- Jean Schneider (2011). "Notes for star 55 Cnc". Extrasolar Planets Encyclopaedia. Archived from the original on September 29, 2007. Retrieved 8 October 2011.
- "55 Cancri". University of Illinois. The Planet Project. Archived from the originalon 17 May 2008. Retrieved 2008-06-12.
- Sanders, Robert (2004-08-31). "Astronomers searching for distant Earths find two Neptunes". UC Berkeley News. Archived from the original on 16 May 2008. Retrieved 2008-06-12.
- Ward Glen (2007-11-08). "Astronomers Find Fifth Planet Around 55 Cancri". The Starry Mirror. Archived from the original on 2007-11-10. Retrieved 2008-06-12.
- When the Gods Fall 55 Cancri in fiction.
- Extrasolar Planet Interactions by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona
- The First and the second part of a computer animation of the 55 Cancri planetary system.
- Interactive visualisation of the 55 Cancri system