Lihat sumber Albireo

{{Starbox 2
| name=Albireo A
| image=[[Berkas:Position beta Cyg.png|250px]]
| caption=Albireo's position, lower right corner. {{br}} The cross-like figure is the Northern Cross. {{br}} The blue line shows the boundaries of the constellation the Swan.
| epoch=[[J2000.0]] ([[International Celestial Reference System|ICRS]])
| constell=[[Cygnus (constellation)|Cygnus]]
| ra_a_h=19
| ra_a_m=30
| ra_a_s=43.281
| dec_a_d=+27
| dec_a_m=57
| dec_a_s=34.85
| radec_a_footnote=<ref name=viziera>[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/h_dm_com&recno=19929 HIP 95947, record for component 1], [[Hipparcos catalogue]]; [[Centre de Données astronomiques de Strasbourg|CDS]] ID [http://vizier.u-strasbg.fr/viz-bin/Cat?I/239 I/239].</ref>
| ra_b_h=19
| ra_b_m=30
| ra_b_s=43.302
| dec_b_d=+27
| dec_b_m=57
| dec_b_s=34.61
| radec_b_footnote=<ref name=vizierb>[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=I/239/h_dm_com&recno=19930 HIP 95947, record for component 2], [[Hipparcos catalogue]]; [[Centre de Données astronomiques de Strasbourg|CDS]] ID [http://vizier.u-strasbg.fr/viz-bin/Cat?I/239 I/239].</ref>
| prop_mo_ra_a=−7.09<ref name=viziera />
| prop_mo_dec_a=−5.63<ref name=viziera />
| prop_mo_ra_b=5.04<ref name=vizierb />
| prop_mo_dec_b=6.48<ref name=vizierb />
| parallax=8.46
| p_error=0.58
| class_a=K3III<ref name=wds>Entry, [http://ad.usno.navy.mil/wds/wdsnewframe4.html The Washington Double Star Catalog], identifier 19307+2758, discoverer identifier MCA  55.  Accessed on line [[July 9]], [[2008]].</ref>
| class_b=B0V<ref name=wds />
| parallax_footnote=<ref name=simbada>{{SIMBAD link|HD+183912|CCDM J19307+2758A  -- Double or multiple star}}, database entry, [[SIMBAD]].  Accessed on line [[July 9]], [[2008]].</ref>
|appmag_v_a=3.18<ref name=bsd>Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory, Theo ten Brummelaar, Brian D. Mason, et al., ''Astronomical Journal'' '''119''', #5 (May 2000), pp. 2403–2414.  {{doi|10.1086/301338}}. {{bibcode|2000AJ....119.2403T}}.  See tables 4, 5, 6, and 8.  Luminosity from L<sub>bol</sub>=10<sup>2(4.75−M<sub>bol</sub>)/5</sup>.</ref>
|appmag_v_b=5.82<ref name=bsd />
|v-r_a=0.92<ref name=bsd />
|v-r_b=0.09<ref name=bsd />
|absmag_v_a=−2.18<ref name=bsd />
|absmag_v_b=0.46<ref name=bsd />
|temperature_a=4080±10<ref name=bsd />
|temperature_b=30000±100<ref name=bsd />
|luminosity_bolometric_a=1200±200<ref name=bsd />
|luminosity_bolometric_b=950±250<ref name=bsd />
|mass_a=5<ref name=stars />
|mass_b=3.2<ref name=stars />
|radius_a=16<ref>[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-source=II/224/cadars&recno=8926 Entry, HD 183912], Catalogue of Stellar Diameters (CADARS);  [[Centre de Données astronomiques de Strasbourg|CDS]] ID [http://vizier.u-strasbg.fr/viz-bin/Cat?II/224 II/224].</ref>
|orbit_footnote=<ref name=wdsa>Entry, WDS identifier 19307+2758, [http://ad.usno.navy.mil/wds/orb6/orb6frames.html Sixth Catalog of Orbits of Visual Binary Stars],  William I. Hartkopf & Brian D. Mason, U.S. Naval Observatory.  Accessed on line [[July 9]], [[2008]].</ref>
|period=213.859
|axis_unitless=0.536[[Arcsecond|″]]
|inclination=154.9
|node=170.4
|periastron=B1997.995
|eccentricity=0.256
|periarg=39.4
|names=[[Bayer designation|β&nbsp;Cygni&nbsp;A]], β<sup>1</sup>&nbsp;Cygni, [[Flamsteed designation|6&nbsp;Cygni&nbsp;A]], [[Double star designation|MCA&nbsp;55&nbsp;Aac]], [[Aitken Double Star Catalogue|ADS]]&nbsp;12540&nbsp;A, [[Durchmusterung|BD]]+27&nbsp;3410, [[Catalogue of Components of Double and Multiple Stars|CCDM]]&nbsp;J19307+2758A, [[Catalogues of Fundamental Stars|FK5]]&nbsp;732, [[Henry Draper Catalogue|HD]]&nbsp;183912/183913, [[Hipparcos Catalogue|HIP]]&nbsp;95947, [[Bright Star Catalogue|HR]]&nbsp;7417, NSV&nbsp;12105, [[Smithsonian Astrophysical Observatory Star Catalogue|SAO]]&nbsp;87301, [[Washington Double Star Catalog|WDS]]&nbsp;19307+2758Aa/Ac<ref name=wdsa /><ref name=pisco>Speckle observations with PISCO in Merate: IV. Astrometric measurements of visual binaries in 2005, M. Scardia et al., ''Astronomische Nachrichten'' '''329''', #1 (2008), pp. 54–68.  {{bibcode|2008AN....329...54S}}.  {{doi|10.1002/asna.200710834}}.</ref><ref name=simbada />
| simbad_system = HD+183912
}}

'''Albireo (β Cyg / β Cygni / Beta Cyg / [[beta (letter)|Beta]] Cygni)''' adalah bintang tercerah kelima di rasi [[Cygnus]]. Meskipun oleh Bayer diberikan nama ''beta'', namun sesungguhnya ia adalah bintang yang lebih redup daripada [[Gamma Cygni]], [[Delta Cygni]], dan [[Epsilon Cygni]]. Albireo dipandang oleh mata telanjang sebagai satu bintang, namun oleh binokular, bintang ini terlihat sebagai [[bintang ganda]], terdiri dari bintang kuning cemerlang dan bintang yang berwarna biru redup. Albireo merupakan bintang yang menarik di pandangan astronom amatir dengan menggunakan teleskop<ref name=stars />

== Bintang ganda ==
[[Berkas:NewAlbireo.jpg|120px|thumb|left]]
Albireo berada pada jarak {{convert|380|ly|pc|abbr=off|lk=on}} dari [[Bumi]]. Bintang ganda ini terdiri dari '''Albireo A''' (berwarna kuning dengan [[magnitudo]] 3.1), dan '''Albireo B''' (biru kehijauan, bermagnitudo 5.1.)<ref name=msg />. Terpisah dengan jarak 35 arcsecond, kedua bintang ini menghasilkan warna kontras yang sangat menarik di langit. Diperkirakan periode orbitnya adalah 100,000 years.<ref name=msg>p. 46, ''The Monthly Sky Guide'', Ian Ridpath, Wil Tirion, Cambridge University Press, 2006, ISBN 0-521-68435-8.</ref>

== Albireo A ==
Pada tahun 1976, komponen A ditemukan sebagai [[bintang ganda]], menggunakan ''speckle interferometry'' dan teleskop 2.1 meter di [[Kitt Peak National Observatory]].<ref name=pisco /><ref>Speckle interferometric measurements of binary stars. VI, H. A. McAlister and E. M. Hendry, ''Astrophysical Journal Supplement Series'' '''48''' (March 1982), pp. 273–278. {{bibcode|1982ApJS...48..273M}}. {{doi|10.1086/190778}}.</ref>.

== Albireo B ==
{{Starbox 1
| name=Albireo B
| epoch=[[J2000.0]] ([[International Celestial Reference System|ICRS]])
| constell=[[Cygnus (constellation)|Cygnus]]
| ra={{RA|19|30|45.3954}}<ref name=simbadb>{{SIMBAD link|HD+183914|HD 183914 -- Emission-line Star}}, database entry, [[SIMBAD]].  Accessed on line [[July 9]], [[2008]].</ref>
| dec={{DEC|+27|57|54.995}}<ref name=simbadb />
| appmag_v=5.09<ref name=simbadb />
| class=B8Ve<ref name=simbadb />
|u-b=-0.30<ref>UBV observations of visual double stars, T. E. Lutz, ''Publications of the Astronomical Society of the Pacific'' '''83''' (August 1971), pp. 488–490.  {{bibcode|1971PASP...83..488L}}.</ref>
| b-v=-0.06<ref name=simbadb />
|radial_v=-18<ref name=simbadb />
|prop_mo_ra=-1.95<ref name=simbadb />
|prop_mo_dec=-0.98<ref name=simbadb />
|parallax=8.67
|p_error=0.65
|parallax_footnote=<ref name=simbadb />
|mass=3.3<ref name=stars>[http://www.astro.uiuc.edu/~kaler/sow/albireo.html Albireo], ''Stars'', Jim Kaler.  Accessed on line [[July 9]], [[2008]].</ref>
|luminosity_bolometric=230 ± 90<ref name=physparms />
|temperature=13200 ± 600<ref name=physparms>Table 1, Physical Parameters of Southern B- and Be-Type Stars, R. S. Levenhagen and N. V. Leister, ''The Astronomical Journal'' '''127''', #2 (February 2004), pp. 1176–1180, {{doi|10.1086/381063}}, {{bibcode|2004AJ....127.1176L}}.</ref>
|radius=2.7<ref>[http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-source=II/224/cadars&recno=8927 Entry, HD 183914], Catalogue of Stellar Diameters (CADARS);  [[Centre de Données astronomiques de Strasbourg|CDS]] ID [http://vizier.u-strasbg.fr/viz-bin/Cat?II/224 II/224].</ref>
|gravity = 4.00 ± 0.15<ref name=physparms />
|mass = 3.7 ± 0.8<ref name=physparms />
|rotation=<0.6 [[days]]<ref name=stars />
|age=4×10<sup>7</sup> to 2×10<sup>8</sup> <ref name=physparms />
|primary=Albireo A
|separation_epoch=2006
|posang=54
|posang_footnote=<ref name=wdsb>Entry, [http://ad.usno.navy.mil/wds/wdsnewframe4.html The Washington Double Star Catalog], identifier 19307+2758, discoverer identifier STFA 43.  Accessed on line [[July 9]], [[2008]].</ref>
|angdistsec=35.3
|angdist_footnote=<ref name=wdsb />
|names=[[Bayer designation|β&nbsp;Cygni&nbsp;B]], β<sup>2</sup>&nbsp;Cygni, [[Flamsteed designation|6&nbsp;Cygni&nbsp;B]], [[Double star designation|STF&nbsp;4043B]], [[Aitken Double Star Catalogue|ADS]]&nbsp;12540&nbsp;B, [[Durchmusterung|BD]]+27&nbsp;3411, [[Catalogue of Components of Double and Multiple Stars|CCDM]]&nbsp;J19307+2758B,
[[Henry Draper Catalogue|HD]]&nbsp;183914, [[Hipparcos Catalogue|HIP]]&nbsp;95951, [[Bright Star Catalogue|HR]]&nbsp;7418, [[Smithsonian Astrophysical Observatory Star Catalogue|SAO]]&nbsp;87302, [[Washington Double Star Catalog|WDS]]&nbsp;19307+2758B<ref name=wdsb /><ref name=simbadb />
|simbad=HD+183914
}}
Albireo B merupakan bintang yang berotasi cepat, dengan kecepatan rotasi ekuatorial kurang lebih 250 per detik.<ref name=stars>[http://www.astro.uiuc.edu/~kaler/sow/albireo.html Albireo], ''Stars'', Jim Kaler. Accessed on line [[July 9]], [[2008]].</ref> Temperaturnya diperkirakan sekitar 13,200 Kelvin.

== Nama dan etimologi ==
Sejak [[Cygnus]] dijadikan rasi berbentuk angsa, dan Albireo diletakkan di atas kepala (rasi) angsa tersebut, Albireo kadang-kadang disebut sebagai "bintang di paruh (sang bebek)".<ref>p. 416, ''In Quest of the Universe'', Theo Koupelis and Karl F. Kuhn, 5th ed., 	Sudbury, Massachusetts: Jones & Bartlett Publishers, 2007, ISBN 0-7637-4387-9.</ref> 

Astronom pada masa Arab kuno menyebut Albireo adalah ''minqār al-dajāja<sup>h</sup>'', yang berarti "paruh ayam"<ref>p. 196, [http://books.google.com/books?id=5xQuAAAAIAAJ ''Star-names and Their Meanings''], Richard Hinckley Allen, New York, G. E. Stechert, 1899.</ref> Nama tersebut merupakan mistranslasi. Mereka mengira bahwa Cygnus berasal dari nama ''ornis'' yang di-Arab-kan menjadi ''urnis''.<ref>p. 24, [http://books.google.com/books?id=9EUDAAAAQAAJ ''The names of the stars and constellations compiled from the Latin, Greek and Arabic''], W. H. Higgins, Leicester: Samuel Clarke, 1882.</ref> Ketika diterjemahkan dalam [[bahasa Latin]], nama ini merujuk kepada sejenis tanam ''[[Erysimum officinale]]'', dan kemudian dirujukanlah nama ini untuk tanaman tersebut, ''ireo''. Kalimat ''ab ireo'' kemudian di-Arab-kan menjadi ''al-bireo''.<ref>p. 194, Allen.</ref>Nama lainnya untuk bintang ini adalah :

{| class="wikitable"
|-
! nama lain
! asal bahasa
! arti
|-
|輦道增七 / Niǎndàozēngqī||[[China]] ||bintang ketujuh (lanjutan) pada rasi [[Daftar asterisme di Sapi#Jalan Terusan Kerajaan|Jalan Terusan Kerajaan]]<ref name=sb0>salah satu rasi bintang menurut bangsa Cina</ref>
|-
|Rostrum Gallinae||[[Bahasa Latin|Latin]] ||paruh ayam<ref>http://articles.adsabs.harvard.edu//full/1895MNRAS..55..429K/0000431.000.html</ref>
|}
Selain [[rasi]] [[Cygnus]], bintang ini juga merupakan anggota dari berbagai rasi atau asterisma berikut :

{| class="wikitable"
|-
! nama rasi / asterisma
! asal 
! arti
! anggota lainnya
|-
| Northern Cross<ref>[http://www.daviddarling.info/encyclopedia/N/Northern_Cross.html Northern Cross], entry, ''The Internet Encyclopedia of Science'', David Darling.  Accessed on line [[July 24]], [[2008]].</ref>||  ||salib di utara||[[Alpha Cygni|α Cyg]], [[Delta Cygni|δ Cyg]], [[Epsilon Cygni|ε Cyg]]
|-
| Al Fawāris|| [[Bahasa Arab|Arab]] ||pengendara||[[Alpha Cygni|α Cyg]], [[Gamma Cygni|γ Cyg]], [[Epsilon Cygni|ε Cyg]], [[Delta Cygni|δ Cyg]], [[Zeta Cygni|ζ Cyg]], [[Kappa Cygni|κ Cyg]], [[Eta Cygni|η Cyg]]
|}

== Referensi ==
{{reflist}}

== Pranala luar ==
* [http://adsabs.harvard.edu/abs/1980S&T....59..210W Albireo as a Triple Star]
* [http://antwrp.gsfc.nasa.gov/apod/ap050830.html Photo by Richard Yandrick; August 30, 2005]
* [http://www.photomeeting.de/astromeeting/double/050728betCYGa1024.htm A picture of Albireo by Stefan Seip]
* [http://www.nightskyinfo.com/archive/albireo NightSkyInfo.com - Albireo]
* [http://www.alcyone-software.com/cgi-bin/search.pl?object=HR7417 Albireo] at Alcyone Software's Star Data Pages
{{commons|Albireo|Albireo}}

[[Kategori:Rasi bintang Cygnus]]
[[Kategori:Bintang ganda]]

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[[fr:Beta Cygni]]
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