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←Membuat halaman berisi '{{Starbox begin | name=Epsilon Eridani }} {{Starbox image | image = 250px | caption = Posisi ε Eridani }} {{Starbox observe | epoc...'
 
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(45 revisi perantara oleh 24 pengguna tidak ditampilkan)
Baris 1:
{{Starbox begin
| name=Epsilonε Eridani
}}
{{Starbox image
| image=
| image = [[File:Eridanus epsilon location.png|250px]]
{{Location mark
| caption = Posisi ε Eridani
|image=Eridanus constellation map.svg|alt=|float=center|width=225
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=ε Eri
|x=568|y=231
}}
|caption=Lokasi bintang ε Eridani (dilingkari)
|alt=
}}
{{Starbox observe
| epoch=[[J2000.0]]
| constell=[[Eridanus (constellation)|Eridanus]]
| ra={{RA|03|32|55.844284496}}<ref name=SIMBADaaa474_2_653 />{{cite web
| dec={{DEC|−09|27|29.7312}}<ref name=aaa474_2_653 />
| url=http://simbad3.u-strasbg.fr/sim-id.pl?protocol=html&Ident=HD+22049
| appmag_v=3.736<ref name=saaoc8_59 />
| title=V* eps Eri -- Variable of BY Dra type
}}
| work=[[SIMBAD]]
| publisher=[[Centre de Données astronomiques de Strasbourg]]
| accessdate=2009-05-20
}}</ref>
| dec={{DEC|&minus;09|27|29.744 }}<ref name=SIMBAD/>
| appmag_v=3.73<ref name=SIMBAD/> }}
{{Starbox character
| engvar = en-UK
| class=K2V<ref name=SIMBAD/>
| class=K2V<ref name=aj132_1_161 />
| appmag_1_passband = B
| appmag_1_passband=B
| appmag_1 = ~4.61<ref name=SIMBAD/>
| appmag_1 =4.61<ref name=SIMBAD />
| appmag_2_passband = V
| appmag_2_passband=V
| appmag_2 = ~3.73<ref name=SIMBAD/>
| appmag_2 =3.73<ref name=SIMBAD />
| appmag_3_passband = J
| appmag_3_passband=J
| appmag_3 = 2.228 ±0.298<ref name=SIMBAD/>
| appmag_3 ={{nowrap|2.228 ±0.298}}<ref name=cutri2003 />
| appmag_4_passband = H
| appmag_4_passband=H
| appmag_4 = 1.880 ±0.276<ref name=SIMBAD/>
| appmag_4 ={{nowrap|1.880 ± 0.276}}<ref name=cutri2003 />
| appmag_5_passband = K
| appmag_5_passband=K
| appmag_5 = 1.776 ±0.286<ref name=SIMBAD/>
| b-vappmag_5 =+{{nowrap|1.776 ± 0.88286}}<ref name=apj83>{{citecutri2003 journal/>
| b-v=+0.887<ref name=saaoc8_59 />
| last=Mendoza | first=E. E.
| u-b=+0.571<ref name=saaoc8_59 />
| coauthors=Gomez, V. T.; Gonzalez, S.
| variable=[[Variabel BY Draconis|BY Dra]]<ref name=SIMBAD /><ref name=gcvs />
| title=UBVRI photometry of 225 Am stars.
}}
| journal=Astronomical Journal
| year=1978
| volume=83
| pages=606–614
| url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?1978AJ.....83..606M
| accessdate=2007-11-29
| doi=10.1086/112242
}}</ref>
| u-b=+0.58<ref name=apj83/>
| r-i=+0.42
| v-r=+0.50
| variable=[[BY Draconis variable|BY]]<ref name=SIMBAD/><ref name="GCVS"/> }}
{{Starbox astrometry
| radial_v={{nowrap|+15.5&plusmn; ± 0.9}}<ref name=SIMBADrgcrv66 />
| prop_mo_ra=&minus;976−975.3617<ref name=SIMBADaaa474_2_653 />
| prop_mo_dec=1719.9849<ref name=SIMBADaaa474_2_653 />
| parallax=310311.7437
| p_error=0.851
| parallax_footnote=<ref name=SIMBADaj132_2206 />
| absmag_v=6.19<ref name=RECONS />
}}
{{Starbox detail
| age=(0.5–1.0){{Esp|9}}400–800 juta<ref name=aaa426>{{cite"Janson2015" journal/>
| metal={{nowrap|−0.13 ± 0.04}}<ref name=aaa415 /> [[notasi ilmiah|dex]]
| author=Di Folco, E. ''et al.''
| mass={{nowrap|0.82 ± 0.02}}<ref name=mnras403_3_1368 /><ref name=Baines />
| title=VLTI near-IR interferometric observations of Vega-like stars. Radius and age of α PsA, β Leo, β Pic, &epsilon; Eri and τ Cet
| radius={{nowrap|0.735 ± 0.005}}<ref name=aaa505_1_205 />
| journal=Astronomy and Astrophysics | year=2004
| rotation=11.2 hari<ref name=an328_10 />
| volume=426 | pages=601–617
| rotational_velocity={{nowrap|2.4 ± 0.5}}<ref name=an328_10 />
| url=http://adsabs.harvard.edu/abs/2004A&A...426..601D
| gravity={{nowrap|4.30 ± 0.08}}<ref name=mnras403_3_1368 />
| accessdate=2008-07-24
| luminosity=0.34<ref name=apj460_993 />
| doi=10.1051/0004-6361:20047189 }}</ref>
| metaltemperature=[Fe/H]=&minus;0.13{{nowrap|5,084 ±0 5.049}}<ref name=aaa415>{{citeaaa411_3_559 journal/>
| last=Santos | first=N. C.
| coauthors=Israelian, G.; Mayor, M.
| title=Spectroscopic <nowiki>[Fe/H]</nowiki> for 98 extra-solar planet-host stars: Exploring the probability of planet formation
| journal=Astronomy & Astrophysics | year=2004 | volume=415
| pages=1153–1166
| url=http://arxiv.org/abs/astro-ph/0311541
| accessdate=2007-11-29
| doi=10.1051/0004-6361:20034469
}}&mdash;the percentage of iron is given by <math>\begin{smallmatrix}10^{-0.13} = 0.74\end{smallmatrix}</math>, or 74%</ref>
| mass=0.85<ref name=RECONS>{{cite web
| author=Staff | date=[[June 8]], [[2007]]
| url=http://www.chara.gsu.edu/RECONS/TOP100.posted.htm
| title=The One Hundred Nearest Star Systems
| publisher=Research Consortium on Nearby Stars
| accessdate=2007-11-29 }}</ref>
| radius=0.84<ref name=apjss53>{{cite journal
| last=Johnson | first=H. M. | coauthors=Wright, C. D.
| title=Predicted infrared brightness of stars within 25 parsecs of the sun
| journal=Astrophysical Journal Supplement Series
| year=1983 | volume=53 | pages=643–711
| url=http://adsbit.harvard.edu/abs/1983ApJS...53..643J
| accessdate=2007-11-29
| doi=10.1086/190905 }}&mdash;see p. 653.</ref>
| rotation=11.1 days
| gravity=4.57<ref>{{cite journal
| author=Zhao, G.; Chen, Y. Q.; Qiu, H. M.; Li, Z. W.
| title=Chemical Abundances of 15 Extrasolar Planet Host Stars
| journal=The [[Astronomical Journal]] | year=2002
| volume=124 | issue=4 | pages=2224–2232
| url=http://www.journals.uchicago.edu/doi/full/10.1086/342862
| accessdate=2007-06-01
| doi=10.1086/342862
}}</ref>
| luminosity=0.28
| temperature=5073±42<ref name=aaa415/> }}
{{Starbox reference
| Simbad = HD+22049
| EPE=eps+Eridani
}}
{{Starbox catalog
| names = Ran, [[FlamsteedPenamaan designationFlamsteed|18&nbsp;Eridani]], [[Bonner Durchmusterung|BD]]&nbsp;-09°697, [[General Catalogue of Trigonometric Parallaxes|GCTP]]&nbsp;742.00, [[Gliese-Jahreiss catalogue|GJ]]&nbsp;144, [[Henry Draper catalogue|HD]]&nbsp;22049, [[Hipparcos catalogue|HIP]]&nbsp;16537, [[Harvard Revised catalogue|HR]]&nbsp;1084, [[Luyten Half-Second catalogue|LHS]]&nbsp;1557, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;130564, [[Washington Double Star Catalog|WDS]]&nbsp;03330-0928.<ref name=SIMBAD />
}}
{{Starbox reference
| Simbad = HD+22049|sn=The star
| Simbad2=*+eps+Eri+b|sn2=planet b
| Simbad3=*+eps+Eri+c|sn3=planet c
}}
{{Starbox end}}
 
'''Epsilon Eridani''' ('''ε EriEridani''', /disingkat '''Epsilon Eri''', '''ε EridaniEri'''), lebih dikenal dengan nama '''Ran''' {{IPAc-en|ˈ|r|ɑː|n}},<ref name="IAU-CSN">{{cite web|url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt|title=IAU Catalog of Star Names|accessdate=July 28, 2016}}</ref> adalah bintang [[deret utama|deret-utama]] dengan [[klasifikasi spektrum|kelas spektrum]] K2. Berjarak sekitar 10.5 tahun cahaya dari matahariMatahari, merupakan rasi bintang [[Eridanus (rasi bintang)|Eridanus]], asserta wellbintang asterdekat theketiga thirdyang [[List of nearest stars|closest star]] yangdapat nampakdilihat dengan mata telanjang. Usianya diperkirakan setidaknya kurang dari satu milyarmiliar tahun. BecauseDikarenakan ofmasih itsrelatif relative youthmuda, Epsilon Eridani hasmemiliki aaktivitas highermagnetik levelyang oflebih magnetictinggi activity than thedari [[SunMatahari]], with adengan [[stellarangin windsurya]] 30 timeskali aslebih strongkuat. ItsPeriode rotationrotasinya periodrelatif is a relatively rapidcepat 11.1&nbsp;days, although this varies by latitudehari. Epsilon Eridani is both smaller and less massive than the Sun, with a lower [[metallicity]] (enrichment in elements heavier than [[helium]]).<ref name="aaa426" />
 
[[Berkas:Size epsilon eridani.png|kiri|jmpl|Ukuran relatif Epsilon Eridani (kiri) dibandingkan dengan Matahari (kanan).]]
[[Methods of detecting extrasolar planets#radial velocity|Radial velocity]] observations over the past 20 years yield evidence of a gas giant planet orbiting Epsilon Eridani, making it the nearest extrasolar system with a candidate [[exoplanet]].<ref name="Hatzes2000" /> This object, conventionally known as [[Epsilon Eridani b]], was formally announced in 2000 by a team of astronomers led by Artie Hatzes.<ref name="Hatzes2000" /> However, the radial velocity data contain a high level of background noise due to the star's magnetic activity, and the proposed planet is not universally accepted.<ref name="Backman2008">Backman D, Marengo M, Stapelfeldt K, Su K, Wilner D, Dowell CD, Watson D, Stansberry J, Rieke G, Megeath T, Fazio G, Werner M. (2008) "Epsilon Eridani’s planetary debris disk: Structure and dynamics based on Spitzer and CSO observations." Astrophysical Journal, in press. Abstract at http://adsabs.harvard.edu/abs/2008arXiv0810.4564B</ref> Current data indicate that this planet orbits in a period of about 7 years at a mean separation of 3.4 [[astronomical units]] (AU), corresponding to 505&nbsp;million&nbsp;kilometers.<ref>Encyclopaedia of Extrasolar Planets at http://exoplanet.eu/star.php?st=Epsilon+Eridani</ref>
Epsilon Eridani diperkirakan memiliki 85% dari masa Matahari<ref name=RECONS/> dan radiusnya 84% dari radius Matahari,<ref name=apjss53/> tetapi memiliki hanya 28% tingkat [[luminositas]] dibanding Matahari. Bintang ini merupakan bintang K dengan kelas spektrum terdekat, setelah [[Alpha Centauri|Alpha Centauri B]].<ref name=RECONS/> kandungan [[metallisitas]] atau zat-zat yang lebih berat dari [[helium]] sedikit lebih rendah dari Matahari, dengan tingkat [[kromosferik]] [[besi]] diperkirakan 74% dari Matahari.<ref name=aaa415/>
 
== Etimologi ==
The system also includes two debris belts composed of rocky asteroids, one at about 3&nbsp;AU and the second at about 20&nbsp;AU, whose structure may be maintained by a hypothetical second planet.<ref>{{cite web
| first=David A. | last=Aguilar
| coauthors=Pulliam, Christine | date=2008-10-27 | url=http://www.cfa.harvard.edu/press/2008/pr200822.html
| title=Solar system's young twin has two asteroid belts
| publisher=[[Harvard-Smithsonian Center for Astrophysics]]
| accessdate=2008-11-10 }}</ref> In addition, Epsilon Eridani harbors an extensive outer debris disk corresponding to the Solar System's [[Kuiper belt]].<ref name="Backman2008" /> The density of orbiting material, which is considerably more than that around the Sun, corroborates the star's youth.
 
Bintang ini memiliki nama tradisional '''Sadira''' atau '''Al Sadirah''', berasal dari [[bahasa Arab]] yang berarti "burung unta yang lari dari air". Nama lainnya untuk bintang ini adalah:
As one of the nearest Sun-like stars, Epsilon Eridani regularly appears in [[science fiction]]. Its closest neighbor is the M dwarf binary system [[Luyten 726-8]], at a distance of about 5 light years.<ref>Data at http://www.solstation.com/stars/eps-erid.htm, accessed on November 28, 2008.</ref>
 
{| class="wikitable"
== Observation ==
|-
This star is located in the northern part of the constellation Eridanus, about 3° east of the slightly brighter star [[Delta Eridani]]. With a declination of &minus;9.45°, Epsilon Eridani can be viewed from much of the Earth's surface. Only to the north of [[80th parallel north|latitude 80&deg;&nbsp;N]] is it permanently hidden below the horizon.<ref>{{cite book
! nama lain
| first=William Wallace | last=Campbell | year=1899
! asal bahasa
| title=The Elements of Practical Astronomy
! arti
| publisher=The MacMillan Company
|-
| location=New York }}</ref> The [[apparent magnitude]] of 3.73 can make this star difficult to observe from an urban area with the unaided eye, as the night skies over cities are illuminated by [[light pollution]].<ref>{{cite book
|天苑三 / Tiānyuànsān||[[China]] ||bintang ketiga pada rasi [[Daftar asterisme di Kepala yang Berambut#Padang Rumput di Langit|Padang Rumput di Langit]]<ref>salah satu rasi bintang menurut bangsa Cina</ref>
| first=Kohei | last=Narisada
|}
| coauthors=Schreuder, Duco | year=2004
Selain rasi [[Eridanus]],bintang ini juga merupakan anggota dari berbagai rasi, asterisma atau kelompok berikut:
| title=Light Pollution Handbook
| publisher=Springer
| isbn=140202665X }}</ref>
 
{| class="wikitable"
The [[Bayer designation]] for this star was established in 1603 as part of the ''[[Uranometria]]'', a star catalog produced by [[Johann Bayer]]. Epsilon is the fifth letter in the [[Greek alphabet]], and it was assigned to the fifth brightest star in the constellation of Eridanus.<ref>{{cite book
|-
| first=Nick | last=Kanas | year=2007
! nama lain
| title=Star Maps: History, Artistry, and Cartography
! asal bahasa
| publisher=Springer
! arti
| isbn=0387716688 }}</ref> The preliminary version of the star catalog by [[John Flamsteed]], published in 1712, gave this star the [[Flamsteed designation]] 18&nbsp;Eridani.<ref name=SIMBAD/> In 1918 this star appeared in the ''[[Henry Draper Catalogue]]'' with the designation HD&nbsp;22049 and a preliminary [[spectral classification]] of K0.<ref>{{cite journal
! anggota lain
| last=Cannon | first=Annie J.
|-
| coauthors=Pickering, Edward C.
|天苑 / Tiānyuán||[[China]] ||[[Daftar asterisme di Kepala yang Berambut#Padang Rumput di Langit|Padang Rumput di Langit]]||[[Gamma Eridani|γ Eri]], [[Pi Eridani|π Eri]], [[Delta Eridani|δ Eri]], [[Zeta Eridani|ζ Eri]], [[Pi Ceti|π Cet]], [[Eta Eridani|η Eri]], [[Tau1 Eridani|τ<sup>1</sup> Eri]], [[Tau2 Eridani|τ<sup>2</sup> Eri]], [[Tau3 Eridani|τ<sup>3</sup> Eri]], [[Tau4 Eridani|τ<sup>4</sup> Eri]], [[Tau5 Eridani|τ<sup>5</sup> Eri]], [[Tau6 Eridani|τ<sup>6</sup> Eri]], [[Tau7 Eridani|τ<sup>7</sup> Eri]], [[Tau8 Eridani|τ<sup>8</sup> Eri]], [[Tau9 Eridani|τ<sup>9</sup> Eri]]
| title=The Henry Draper catalogue 0h, 1h, 2h, and 3h
|-
| journal=Annals of Harvard College Observatory
|Cītlalmazātl ||[[Aztec]]||rusa||[[Gamma Eridani|γ Eri]], [[Delta Eridani|δ Eri]], [[Upsilon4 Eridani|υ<sup>4</sup> Eri]]+, [[Phi Eridani|φ Eri]], [[Chi Eridani|χ Eri]]+, [[Tau4 Eridani|τ<sup>4</sup> Eri]]+, [[Upsilon2 Eridani|υ<sup>2</sup> Eri]]+, [[Eta Eridani|η Eri]], [[43 Eridani|43 Eri]]+, [[Tau3 Eridani|τ<sup>3</sup> Eri]]+, [[Tau6 Eridani|τ<sup>6</sup> Eri]]+, [[Tau5 Eridani|τ<sup>5</sup> Eri]]+, [[Tau1 Eridani|τ<sup>1</sup> Eri]]+, [[Tau2 Eridani|τ<sup>2</sup> Eri]], [[Tau9 Eridani|τ<sup>9</sup> Eri]]+, [[Alpha Fornacis|α For]], [[Beta Fornacis|β For]], [[Kappa Fornacis|κ For]]+, [[Chi2 Fornacis|χ<sup>2</sup> For]]+, [[Chi1 Fornacis|χ<sup>1</sup> For]]+, [[Chi3 Fornacis|χ<sup>3</sup> For]]+
| year=1918 | volume=91 | pages=1–290
|}
| url=http://adsabs.harvard.edu/abs/1918AnHar..91....1C
+ berkemungkinan merupakan anggota
| accessdate=2008-07-21 }}&mdash;see p. 236</ref>
 
== Referensi ==
Based on observations between 1800 and 1880, Epsilon Eridani was found to have a large [[proper motion]], which at the time was estimated at three [[arcsecond]]s annually. This implied a relatively close proximity to the Sun,<ref>{{cite book
{{reflist|colwidth=25em|refs=
| first=Leila | last=Belkora | year=2002
| title=Minding the Heavens: The Story of Our Discovery of the Milky Way
| publisher=CRC Press | isbn=0750307307 }}</ref> making it a star of interest for the purpose of trigonometric [[parallax]] measurements.<ref>{{cite journal
| last=Gill | first=David | coauthors=Elkin, W. L.
| title=Heliometer Determinations of Stellar Parallaxes in the Southern Hemisphere
| journal=Memoirs of the Royal Astronomical Society
| year=1884 | volume=48 | pages=77–115
| url=http://books.google.com/books?id=F60RAAAAYAAJ
| accessdate=2008-07-21
}}&mdash;see pp. 174&ndash;80</ref> From 1881&ndash;3, [[William Lewis Elkin|William L. Elkin]] made a series of heliometric measurements from the Royal Observatory at the [[Cape of Good Hope]], [[South Africa]]. As a result of these observations, a preliminary parallax of 0.14&nbsp;±&nbsp;0.02&nbsp;arcseconds was computed for Epsilon Eridani.<ref>{{cite book
| first=David | last=Gill | year=1893
| title=Heliometer Observations for Determination of Stellar Parallax
| publisher=Eyre and Spottiswoode | location=London }}</ref><ref>{{cite journal
| last=Gill | first=David | title=The Fixed Stars
| journal=Nature | year=1884 | volume=30
| pages=156–159
| doi=10.1038/030156a0 }}</ref> By 1917, observers had refined their parallax estimate to 0.317&nbsp;arcseconds,<ref>{{cite journal
| last=Adams | first=W. S. | coauthors=Joy, A. H.
| title=The luminosities and parallaxes of five hundred stars.
| journal=Astrophysical Journal | year=1917
| volume=46 | pages=313–339
| url=http://adsabs.harvard.edu/abs/1917ApJ....46..313A
| accessdate=2008-07-19
| doi=10.1086/142369 }}</ref> which is quite close to the modern value of 0.3107&nbsp;arcseconds.<ref name=SIMBAD/> This parallax is equivalent to a distance of about 10.5&nbsp;[[light year]]s, making Epsilon Eridani the 13th nearest known star (and ninth nearest [[stellar system]]) to the Sun.<ref name=RECONS/>
 
<ref name="Janson2015">{{citation
In 1960, [[Project Ozma]], headed by Dr. [[Frank Drake]], used a radio telescope
| display-authors=1
at [[Green Bank, West Virginia]], to search for signals from putative [[extraterrestrial intelligence]]s. Its target stars were Epsilon Eridani and [[Tau Ceti]]. However, no signals of extraterrestrial origin were detected.<ref>{{cite book
| last1=Janson | first1=Markus
| first=Jean | last=Heidmann | coauthors=Dunlop, Storm
| last2=Quanz | first2=Sascha P.
| year=1995 | title=Extraterrestrial intelligence
| last3=Carson | first3=Joseph C.
| publisher=Cambridge University Press
| last4=Thalmann | first4=Christian
| isbn=0521585635 }}</ref>
| last5=Lafrenière | first5=David
| last6=Amara | first6=Adam
| title=High-contrast imaging with Spitzer: deep observations of Vega, Fomalhaut, and ε Eridani
| journal=Astronomy & Astrophysics
| volume=574 | id=A120 | pages=10 | date=February 2015
| doi=10.1051/0004-6361/201424944
| bibcode=2015A&A...574A.120J
| arxiv = 1412.4816
| postscript=.
}}</ref>
 
<ref name=rgcrv66>{{citation
In 1983, [[NASA]]'s orbiting telescope [[IRAS]] detected excess infrared emissions originating from Epsilon Eridani, indicating the presence of an orbiting disk of fine-grained dust.<ref name="Neugebauer1984">Neugebauer G, Habing HD, van Duinen R, Aumann HH, Baud B, Beichman CA, et al. (1984) "The Infrared Astronomical Satellite (IRAS) Mission." Astrophysical Journal 278, L1-L6. Abstract at http://adsabs.harvard.edu/abs/1984ApJ...278L...1N.</ref><ref name="Aumann1985">Aumann HH. (1985) IRAS observations of matter around nearby stars. Publications of the Astronomical Society of the Pacific, 97: 885-891. Abstract at http://adsabs.harvard.edu/abs/1985PASP...97..885A.</ref> This so-called [[debris disk]] has been extensively studied since that time.
| last1=Evans | first1=D. S.
| date=June 20–24, 1966 | editor1=Batten, Alan Henry |editor2=Heard, John Frederick | title=The revision of the general catalogue of radial velocities | work=Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 | place=University of Toronto | publisher=[[International Astronomical Union]] | bibcode=1967IAUS...30...57E | volume=30 | pages=57 | postscript=. }}</ref>
 
<ref name=mnras403_3_1368>{{citation
In 1995, based on its location within 7.2&nbsp;pc, Epsilon Eridani was among the target stars of [[Project Phoenix (SETI)|Project Phoenix]], a microwave survey for signals from extraterrestrial intelligence.<ref>{{cite conference
| last1=Gonzalez | first1=G.
| author=Henry, T. ''et al.''
| last2=Carlson | first2=M. K.
| title=The Current State of Target Selection for NASA's High Resolution Microwave Survey
| last3=Tobin | first3=R. W.
| booktitle=Progress in the Search for Extraterrestrial Life
| title=Parent stars of extrasolar planets – X. Lithium abundances and v sini revisited | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=403 | issue=3 | pages=1368–1380 |date=April 2010 | doi=10.1111/j.1365-2966.2009.16195.x | bibcode=2010MNRAS.403.1368G | arxiv=0912.1621 | postscript=. }} See table 3.</ref>
| pages=207–218
| publisher=Astronomical Society of the Pacific
| date=August 16-20,1993 | location=Santa Cruz, California
| url=http://adsabs.harvard.edu/abs/1995ASPC...74..207H
| accessdate=2008-07-22 }}</ref> By 2004 Project Phoenix had checked about 800 stars, but had not yet detected an unimpeachable signal.<ref>{{cite news
| last=Whitehouse | first=David | date=2004-03-25
| title=NASA's Hubble Space Telescope Finds "Blue Straggler" Stars in the Core of a Globular Cluster
| publisher=BBC News
| url=http://news.bbc.co.uk/1/hi/sci/tech/3567729.stm
| accessdate=2008-07-22 }}</ref>
 
<ref name=saaoc8_59>{{citation | last1=Cousins | first1=A. W. J. | title=Standardization of Broadband Photometry of Equatorial Standards | journal=South African Astronomical Observatory Circulars | volume=8 | page=59 | year=1984 | bibcode=1984SAAOC...8...59C | postscript=. }}</ref>
Based on [[Perturbation (astronomy)|perturbation]]s in the position of Epsilon Eridani between 1938 and 1972, it was suspected that the star had an unseen companion with an orbital period of 25&nbsp;years.<ref>{{cite journal
| last=van de Kamp | first=P.
| title=Parallax and orbital motion of Epsilon Eridani.
| journal=Astronomical Journal | year=1974
| volume=79 | pages=491–492
| url=http://adsabs.harvard.edu/abs/1974AJ.....79..491V
| accessdate=2008-07-28
| doi=10.1086/111571 }}</ref> However, this claim
was refuted in 1993. [[Radial velocity]] observations between 1980 and 2000 then provided convincing evidence of a planet orbiting the star with a period of about seven years.<ref name="Hatzes2000">{{cite journal
| author=Hatzes, Artie P. ''et al.''
| title=Evidence for a Long-period Planet Orbiting Epsilon Eridani
| journal=The Astrophysical Journal | year=2000
| volume=544 | issue=2 | pages=L145–L148
| doi=10.1086/317319 }}</ref> The evidence for a planetary system was further strengthened in 1998 by the discovery of asymmetries in the dust ring around star. These clumps of dust could be explained by interaction with a planet orbiting just inside the dust ring.<ref>{{cite news
| last=Greaves | first=Jane | date=1998-07-08
| title=Astronomers discover a nearby star system just like our own Solar System
| url=http://www.jach.hawaii.edu/~jsg/kbelt.html
| publisher=JAC/UCLA | accessdate=2008-07-28 }}</ref>
 
<ref name=aaa474_2_653>{{citation
== Properties ==
| first1=Floor | last1=van Leeuwen
[[Image:Size epsilon eridani.png|left|thumb|The relative size of Epsilon Eridani (left) compared to the Sun (right).]]
|date=November 2007 | title=Validation of the new Hipparcos reduction | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | arxiv=0708.1752v1 | doi=10.1051/0004-6361:20078357 | journal=Astronomy and Astrophysics | postscript=. }} ''Note:'' see VizieR catalogue [http://vizier.u-strasbg.fr/viz-bin/Cat?I/311 I/311].</ref>
Epsilon Eridani has an estimated 85% of the [[solar mass|Sun's mass]]<ref name=RECONS/> and 84% of the [[solar radius|Sun's radius]],<ref name=apjss53/> but only 28% of its [[luminosity]]. It is the second-nearest [[spectral class]] K star, after [[Alpha Centauri|Alpha Centauri B]].<ref name=RECONS/> Its [[metallicity]] or enrichment in elements heavier than [[helium]] is slightly lower than the Sun's, with its [[chromosphere|chromospheric]] abundance of [[iron]] estimated at 74% Solar.<ref name=aaa415/>
 
<ref name=SIMBAD>{{citation | url=http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=V*+eps+Eri | title=V* eps Eri – variable of BY Dra type | work=[[SIMBAD]] | publisher=[[Centre de Données astronomiques de Strasbourg]] | accessdate=November 5, 2010 | postscript=. }}</ref>
The [[chromosphere]] of Epsilon Eridani is more [[Stellar magnetic field|magnetically active]] than the Sun's. Approximately 9% of the deep [[photosphere]] is found to have a magnetic field with a strength about 0.14&nbsp;[[Tesla (unit)|teslas]].<ref>{{cite journal
| last=Valenti | first=Jeff A.
| coauthors=Marcy, Geoffrey W.; Basri, Gibor
| title=Infrared Zeeman analysis of epsilon Eridani
| journal=The Astrophysical Journal, Part 1
| year=1995 | volume=439 | issue=2 | pages=939–956
| url=http://adsabs.harvard.edu/abs/1995ApJ...439..939V
| accessdate=2008-07-19
| doi=10.1086/175231 }}</ref> The overall magnetic activity level of this star is irregular, but it may vary with a five-year period. Assuming that the radius of the star does not change over this interval, then the variation in activity level appears to produce a temperature variation of 15&nbsp;K, which corresponds to a magnitude variation of 0.014.<ref name=apj441>{{cite journal
| last=Gray | first=David F.
| coauthors=Baliunas, Sallie L.
| title=Magnetic activity variations of epsilon Eridani
| journal=Astrophysical Journal, Part 1 | year=1995
| volume=441 | issue=1 | pages=436–442
| url=http://adsabs.harvard.edu/abs/1995ApJ...441..436G
| accessdate=2008-07-19
| doi=10.1086/175368 }}</ref>
 
<ref name=RECONS>{{citation | author=Staff | date=June 8, 2007 | url=http://www.astro.gsu.edu/RECONS/TOP100.posted.htm | title=The one hundred nearest star systems | publisher=[[Research Consortium on Nearby Stars]] | accessdate=November 29, 2007 }}</ref>
Rotational modulation of the magnetic activity suggests that the equator of the star rotates with a period of 11.10&nbsp;±&nbsp;0.03&nbsp;days, which is less than half of the rotation period of the Sun. Stars that vary in magnitude because of magnetic activity coupled with rotation are classified as [[BY Draconis variable]]s.<ref name="GCVS">{{cite web
| url=http://www.sai.msu.su/groups/cluster/gcvs/cgi-bin/search.cgi?search=eps+Eri
| publisher=[[Sternberg Astronomical Institute]], Moscow, Russia
| work=[[General Catalog of Variable Stars]]
| title=GCVS Query=eps Eri
| accessdate=2009-05-20}}</ref> Observations have show this star to vary as much as 0.050 in magnitude due to starspots and other short-term magnetic activity.<ref name="var">{{cite journal
| url=http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1991AJ....102.1813F&amp;data_type=PDF_HIGH&amp;whole_paper=YES&amp;type=PRINTER&amp;filetype=.pdf
| journal= The [[Astrophysical Journal]]
| title=The rotation period of Epsilon ERI from photometry of its starspots
| author=Frey ''et al.''
| year=1991
| month=November
| volume=102
| number=5
| pages=1813-1815}}</ref> [[Photometry (astronomy)|Photometry]] has also shown that the surface of Epsilon Eridani, like the Sun, is undergoing differential rotation. That is, the rotation period at the surface varies by [[latitude]], with the measured periods ranging from 10.8 to 12.3 days.<ref name=apj441/> The [[axial tilt]] of this star remains uncertain, with estimates ranging from a low of 24&deg; up to 72&deg;.<ref>{{cite journal
| last=Froehlich | first=H.-E.
| title=The differential rotation of epsilon Eri from MOST data
| journal=Astronomische Nachrichten
| year=2007 | volume=328 | pages=1037
| url=http://arxiv.org/abs/0711.0806
| accessdate=2008-07-25
| doi=10.1002/asna.200710876 }}</ref>
 
<ref name=aj132_2206>{{citation | display-authors=1
The high level of chromospheric activity, strong magnetic field, and relatively fast rotation rate indicate that this is a young star.<ref>{{cite journal
| last1=Benedict | first1=G. Fritz
| last=Drake | first=Jeremy J. | coauthors=Smith, Geoffrey
| last2=McArthur | first2=Barbara E.
| title=The fundamental parameters of the chromospherically active K2 dwarf Epsilon Eridani
| last3=Gatewood | first3=George
| journal=Astrophysical Journal, Part 1 | year=1993
| last4=Nelan | first4=Edmund
| volume=412 | issue=2 | pages=797–809
| last5=Cochran | first5=William D.
| url=http://adsabs.harvard.edu/abs/1993ApJ...412..797D
| last6=Hatzes | first6=Artie
| accessdate=2008-07-24
| last7=Endl | first7=Michael
| doi=10.1086/172962 }}</ref> Computer models give an
| last8=Wittenmyer | first8=Robert
estimated age of 700–850 million&nbsp;years, although the actual age may be a low as 500 million or as high as a billion years.<ref name=aaa426/> However, the somewhat low abundance of heavy elements is characteristic of a much older star. This anomaly might be caused by a [[diffusion]] process that has transported some of the helium and heavier elements out of the photosphere to a region below the star's outer [[convection zone]].<ref>{{cite web
| last9=Baliunas | first9=Sallie L.
| last=Gai | first=Ning
| last10=Walker | first10=Gordon A. H. | last11=Yang | first11=Stephenson | last12=Kürster | first12=Martin | last13=Els | first13=Sebastian | last14=Paulson | first14=Diane B. |date=November 2006 | title=The extrasolar planet e Eridani b – orbit and mass | journal=The Astronomical Journal | volume=132 | issue=5 | pages=2206–2218 | bibcode=2006AJ....132.2206B | doi=10.1086/508323 | arxiv=astro-ph/0610247 | postscript=. }}</ref>
| coauthors=Bi, Shao-Lan; Tang, Yan-Ke | year=2008
| url=http://adsabs.harvard.edu/abs/2008arXiv0806.1811G
| title=Modeling &epsilon; Eridani and asteroseismic tests of element diffusion
| publisher=SAO/NASA ADS | accessdate=2008-07-24 }}</ref>
 
<ref name=aj132_1_161>{{citation | display-authors=1
Relative to the Sun, the outer atmosphere of Epsilon Eridani appears both larger and hotter. This is caused by a 30-fold higher mass loss rate from the star's [[stellar wind]]. The wind is generating an [[Stellar wind bubble|astrosphere]] that spans about 8,000&nbsp;AU and a [[bow shock]] that lies 1,600&nbsp;AU from the star. At the star's estimated distance from the Earth, this astrosphere would span an angle of 42&nbsp;arcminutes, which is wider than the appearance of a full [[Moon]].<ref>{{cite journal
| lastlast1=WoodGray | firstfirst1=BrianR. EO.
| last2=Corbally | first2=C. J.
| coauthors=Müller, Hans-Reinhard; Zank, Gary P.; Linsky, Jeffrey L.
| last3=Garrison | first3=R. F.
| title=Measured Mass-loss Rates of Solar-like Stars as a Function of Age and Activity
| last4=McFadden | first4=M. T.
| journal=The Astrophysical Journal | year=2002
| volumelast5=574Bubar | pagesfirst5=1–2E. J.
| last6=McGahee | first6=C. E.
| doi=10.1086/340797 }}</ref>
| last7=O'Donoghue | first7=A. A.
| last8=Knox | first8=E. R.
| title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample | journal=[[The Astronomical Journal]] | volume=132 | issue=1 | pages=161–170 |date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G | arxiv=astro-ph/0603770 | postscript=. }}</ref>
 
<ref name=aaa415>{{citation
The [[space velocity]] components of Epsilon Eridani are ''U''&nbsp;=&nbsp;&minus;3&nbsp;km/s, ''V''&nbsp;=&nbsp;+7&nbsp;km/s and ''W''&nbsp;=&nbsp;&minus;20&nbsp;km/s. It is orbiting within the [[Milky Way]] at a mean galactocentric distance of 8.8&nbsp;kpc and an [[orbital eccentricity]] of 0.09.<ref>{{cite journal
| lastlast1=de MelloSantos | firstfirst1=GN. FC. Porto
| last2=Israelian | first2=G.
| coauthors=del Peloso, E. F.; Ghezzi, L.
| last3=Mayor | first3=M.
| title=Astrobiologically Interesting Stars within 10 parsecs of the Sun
| title=Spectroscopic <nowiki>[Fe/H]</nowiki> for 98 extra-solar planet-host stars: Exploring the probability of planet formation | journal=Astronomy and Astrophysics |date=March 2004 | volume=415 | issue=3 | pages=1153–1166 | doi=10.1051/0004-6361:20034469 | arxiv=astro-ph/0311541 | bibcode=2004A&A...415.1153S | postscript=. }}—the percentage of iron is given by <math>\begin{smallmatrix}10^{-0.13} = 0.74\end{smallmatrix}</math>, or 74%</ref>
| journal=Astrobiology | year=2005
| volume=6 | issue=2 | pages=308–331
| url=http://arxiv.org/abs/astro-ph/0511180
| accessdate=2008-07-27
| doi=10.1089/ast.2006.6.308 }}</ref> During the past million years, three stars are believed to have come within two parsecs of Epsilon Eridani. The most recent encounter was with [[Kapteyn's Star]], which approached within about a parsec about 12,500 years ago. None of these encounters are thought to have affected the circumstellar disk.<ref>{{cite conference
| last=Deltorn | first=J.-M. | coauthors=Kalas, P.
| editors=Jayawardhana, Ray; Greene, Thoas
| title=Search for Nemesis Encounters with Vega, epsilon Eridani, and Fomalhaut
| booktitle=Young Stars Near Earth: Progress and Prospects
| pages=227-232 | year=2001
| publisher=Astronomical Society of the Pacific
| location =San Francisco, CA
| url=http://arxiv.org/abs/astro-ph/0105284
| accessdate=2008-07-22 | isbn=1-58381-082-X }}</ref> Epsilon Eridani made its closest approach to the [[Solar System]] about 105,000&nbsp;years ago, when the two stars were separated by seven light years.<ref name=aaa379>{{cite journal
| last=García-Sánchez | first=J.
| coauthors=Weissman, P. R.; Preston, R. A.; Jones, D. L.; Lestrade, J.-F.; Latham, D. W.; Stefanik, R. P.; Paredes, J. M.
| title=Stellar encounters with the solar system
| journal=Astronomy and Astrophysics
| year=2001 | volume=379 | pages=634&ndash;659
| url=http://adsabs.harvard.edu/abs/2001A&A...379..634G
| accessdate=2008-06-12
| doi=10.1051/0004-6361:20011330 }}</ref>
 
<ref name=aaa411_3_559>{{citation | display-authors=1
== Planetary system ==
| last1=Kovtyukh | first1=V. V.
{{PlanetboxOrbit begin}}
| last2=Soubiran | first2=C.
{{PlanetboxOrbit disk
| last3=Belik | first3=S. I.
| disk = Asteroid belt
| last4=Gorlova | first4=N. I.
| periapsis = 3
| title=High precision effective temperatures for 181 F-K dwarfs from line-depth ratios | journal=Astronomy and Astrophysics | volume=411 | issue=3 | pages=559–564 |date=December 2003 | doi=10.1051/0004-6361:20031378 | arxiv=astro-ph/0308429 | bibcode=2003A&A...411..559K | postscript=. }}</ref>
}}
{{PlanetboxOrbit
| exoplanet = [[Epsilon Eridani b|b]]
| mass = 1.55 &plusmn; 0.24
| period = 2502 &plusmn; 10
| semimajor = 3.39 &plusmn; 0.36
| eccentricity = 0.702 ± 0.039?
}}
{{PlanetboxOrbit disk
| disk = Asteroid belt
| periapsis = 20
}}
{{PlanetboxOrbit speculation
| exoplanet = [[Epsilon Eridani c|c]]
| mass = 0.1
| period = 102200?
| semimajor = 40?
| eccentricity = 0.3
}}
{{OrbitboxPlanet disk
| disk = Dust disk
| periapsis = 35
| apoapsis = 100
}}
{{PlanetboxOrbit end}}
 
<ref name=apj460_993>{{citation | display-authors=1
| last1=Saumon | first1=D.
| last2=Hubbard | first2=W. B.
| last3=Burrows | first3=A.
| last4=Guillot6 | first4=T.
| last5=Lunine | first5=J. I.
| last6=Chabrier | first6=G.
| url=http://articles.adsabs.harvard.edu/full/1996ApJ...460..993S
| title=A theory of extrasolar giant planets | journal=The Astrophysical Journal | volume=460 | page=993 |date=April 1996 | doi=10.1086/177027 | bibcode=1996ApJ...460..993S | arxiv=astro-ph/9510046| postscript=. }} See Table A1, p. 21.</ref>
 
<ref name=aaa505_1_205>{{citation | display-authors=1
| last1=Demory | first1=B.-O.
| last2=Ségransan | first2=D.
| last3=Forveille | first3=T.
| last4=Queloz | first4=D.
| last5=Beuzit | first5=J.-L.
| last6=Delfosse | first6=X.;
| last7=di Folco | first7=E.
| last8=Kervella | first8=P.
| last9=Le Bouquin | first9=J.-B.
| last10=Perrier | first10=C. | last11=Benisty | first11=M. | last12=Duvert | first12=G. | last13=Hofmann | first13=K.-H. | last14=Lopez | first14=B. | last15=Petrov | first15=R. | title=Mass-radius relation of low and very low-mass stars revisited with the VLTI | journal=[[Astronomy and Astrophysics]] | volume=505 | issue=1 |date=October 2009 | pages=205–215 | doi=10.1051/0004-6361/200911976 | bibcode=2009A&A...505..205D | arxiv=0906.0602 | postscript=. }} See Table B.1</ref>
 
<ref name=gcvs>{{citation | title=GCVS query=eps Eri | work=[[General Catalog of Variable Stars]]| publisher=[[Sternberg Astronomical Institute]], Moscow, Russia | url=http://www.sai.msu.su/groups/cluster/gcvs/cgi-bin/search.cgi?search=eps+Eri | accessdate=May 20, 2009 | postscript=. }}</ref>
== Catatan kaki and referensi ==
 
{{reflist|2}}
<ref name=cutri2003>{{citation | display-authors=1
| last1=Cutri | first1=R. M.
| last2=Skrutskie | first2=M. F.
| last3=Van Dyk | first3=S.
| last4=Beichman | first4=C. A.
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| last7=Cambresy | first7=L.
| last8=Evans | first8=T.
| last9=Fowler | first9=J.
| last10=Gizis | first10=J. | last11=Howard | first11=E. | last12=Huchra | first12=J. | last13=Jarrett | first13=T. | last14=Kopan | first14=E. L. | last15=Kirkpatrick | first15=J. D. | last16=Light | first16=R. M. | last17=Marsh | first17=K. A. | last18=McCallon | first18=H. | last19=Schneider | first19=S. | last20=Stiening | first20=R. | last21=Sykes | first21=M. | last22=Weinberg | first22=M. | last23=Wheaton | first23=W. A. | last24=Wheelock | first24=S. | last25=Zacarias | first25=N. |date=June 2003 | title=The IRSA 2MASS all-sky point source catalog, NASA/IPAC infrared science archive | url=http://irsa.ipac.caltech.edu/applications/Gator/ | bibcode=2003tmc..book.....C | journal=The IRSA 2MASS All-Sky Point Source Catalog | postscript=. }}</ref>
 
<ref name=Baines>{{citation | last1=Baines| first1=Ellyn K. | last2=Armstrong | first2=J. Thomas | title=Confirming Fundamental Parameters of the Exoplanet Host Star epsilon Eridani Using the Navy Optical Interferometer| journal=The Astrophysical Journal| volume=748 | pages=72 | year=2011| arxiv=1112.0447 |bibcode = 2012ApJ...748...72B |doi = 10.1088/0004-637X/748/1/72 | postscript=. }}</ref>
 
<ref name=an328_10>{{citation
| last1=Fröhlich | first1=H.-E.
| title=The differential rotation of Epsilon Eri from MOST data | journal=[[Astronomische Nachrichten]] | volume=328 | issue=10 | pages=1037–1039 |date=December 2007 | doi=10.1002/asna.200710876 | bibcode=2007AN....328.1037F | arxiv=0711.0806 | postscript=. }}</ref>
 
}}
 
== Pranala luar ==
* {{cite web | url=http://www.jach.hawaii.edu/~jsg/kbelt.html | title=Astronomers discover a nearby star system just like our own Solar System | work=JAC/UCLA | dateformat=mdy | accessdate=24 March 2005 | archiveurl=https://web.archive.org/web/20060503113944/http://www.jach.hawaii.edu/~jsg/kbelt.html | archivedate=2006-05-03 | dead-url=no }}
* {{cite journal | url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1988ApJ...331..902C&db_key=AST&high=38e0b7728702919 | author=Bruce Campbell, G.A.H. Walker, S. Yang | title=A search for substellar companions to solar-type stars | journal=[[Astrophysical Journal]] | volume=331 | issue=Part 1|year=1988|pages=902 &ndash;– 921 | doi=10.1086/166608}}
* {{cite journal | url=http://www.journals.uchicago.edu/doi/full/10.1086/422796 | author=Sean Moran, [[Marc Kuchner]], and [[Matthew J. Holman|Matthew Holman]] | title=The Dynamical Influence of a Planet at Semimajor Axis 3.4 AU on the Dust around ε Eridani | journal=The [[Astrophysical Journal]] | volume=612 | year=2004 | pages=1163 – 1170 | doi=10.1086/422796}}
* {{cite web|url=http://www.solstation.com/stars/eps-erid.htm|title=Epsilon Eridani|publisher=SolStation|dateformat=mdy |accessdate=13 April 2006}}
 
[[Kategori:Rasi bintang Eridanus]]
{{Sky|03|32|55.8442|−|09|27|29.744|10.5}}
 
[[Category:Bayer objects|Eridani, Epsilon]]
[[Category:Eridanus constellation]]
[[Category:HD and HDE objects|022049]]
[[Category:HIP objects|016537]]
[[Category:K-type main sequence stars]]
[[Category:Stars with proper names]]
[[Category:Circumstellar discs]]
[[Category:Planetary systems]]
 
{{bintang-stub}}
[[bn:এপসাইলন এরিড্যানি]]
[[ca:Epsilon Eridani]]
[[cs:Epsilon Eridani]]
[[cy:Epsilon Eridani]]
[[de:Epsilon Eridani]]
[[es:Épsilon Eridani]]
[[fr:Epsilon Eridani]]
[[ko:에리다누스자리 엡실론]]
[[it:Epsilon Eridani]]
[[kk:Садира (жұлдыз)]]
[[hu:Epszilon Eridani]]
[[nl:Epsilon Eridani]]
[[ja:エリダヌス座ε星]]
[[no:Epsilon Eridani]]
[[pl:Epsilon Eridani]]
[[ro:Epsilon Eridani]]
[[ru:Эпсилон Эридана]]
[[sk:Epsilon Eridani]]
[[fi:Epsilon Eridani]]
[[sv:Epsilon Eridani]]
[[vo:Epsilon Eridani]]
[[zh:波江座ε星]]
[[he:אפסילון בארידנוס]]
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