Editing Albireo

{{short description|Double star system in the constellation Cygnus}}
{{Starbox begin
| name = Albireo
}}
{{Starbox image
 | image=
   {{Location mark
     | image=Cygnus constellation map.svg
     | float=center | width=250 | position=right
     | mark=Red circle.svg | mark_width=8 | mark_link=Albireo (star)
     | x%=62.8 | y%=83.6
   }}
 | caption=Location of Albireo (circled in red)
}}
{{Starbox observe 3s
| epoch = [[J2000.0]] ([[International Celestial Reference System|ICRS]])
| equinox = <!--Equinox of coordinates (defaults to epoch)-->
| constell = [[Cygnus (constellation)|Cygnus]]
| component1 = Albireo Aa
| ra1 = {{RA|19|30|43.286}}<ref name=tycho2/>
| dec1 = {{DEC|+27|57|34.84}}<ref name=tycho2/>
| appmag_v1 = 3.21<ref name=drimmel2021/>
| component2 = Albireo Ac
| ra2 = {{RA|19|30|43.295}}<ref name=tycho/>
| dec2 = {{DEC|+27|57|34.62}}<ref name=tycho/>
| appmag_v2 = 5.85<ref name=drimmel2021/>
| component3 = Albireo B
| ra3 = {{RA|19|30|45.3962}}<ref name=edr3B/>
| dec3 = {{DEC|+27|57|54.989}}<ref name=edr3B/>
| appmag_v3 = 5.11<ref name=photometry/>
}}
{{Starbox character
| component = Albireo Aa
| type = [[Bright giant]]
| class = K2II<ref name="ginestet"/>
| v-r = +0.92<ref name=bsd />
| b-v = +1.13<ref name=photometry/>
| component2 = Albireo Ac
| class2 = B8:p<ref name="ginestet"/>
| v-r2 = +0.09<ref name=bsd />
| b-v2 = +0.09<ref name=tycho/>
}}
{{Starbox character
|no_heading=y
| component = Albireo B
| class = B8Ve<ref name=levenhagen/>
| b-v = -0.10<ref name=photometry/>
| u-b = -0.32<ref name=photometry/>
}}
{{Starbox astrometry
 | component = Albireo A
 | radial_v = −23.54<ref name=drimmel2021/>
 | prop_mo_ra = 4.915
 | prop_mo_dec = −11.127
 | pm_footnote = <ref name="DR3"/>
 | parallax = 8.9816
 | p_error = 0.4474
 | parallax_footnote = <ref name="DR3">{{cite Gaia DR3|2026116260337482112}}</ref>
 | dist_ly = {{Val|364.8|15.6|15.3}}
 | dist_pc = {{val|111.9|4.8|4.7}}
 | dist_footnote = <ref name="b-j">{{Cite journal |last1=Bailer-Jones |first1=C. A. L. |last2=Rybizki |first2=J. |last3=Fouesneau |first3=M. |last4=Demleitner |first4=M. |last5=Andrae |first5=R. |date=2021-03-01 |title=Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3 |journal=The Astronomical Journal |volume=161 |issue=3 |pages=147 |doi=10.3847/1538-3881/abd806 |doi-access=free |arxiv=2012.05220 |bibcode=2021AJ....161..147B |issn=0004-6256}} Data about this star can be seen [https://dc.zah.uni-heidelberg.de/gedr3dist/q/cone/form here].<br />Beta<sup>1</sup> Cygni = Gaia DR3 2026116260337482112 <br />Beta<sup>2</sup> Cygni = Gaia DR3 2026113339752723456</ref>
}}
{{Starbox astrometry
 |no_heading=yes
 | component1 = Albireo Aa
 | absmag_v = −2.45<ref name="ginestet"/>
 | component2 = Albireo Ac
 | absmag_v2 = −0.25<ref name="ginestet"/>
}}
{{Starbox astrometry|no_heading=y
 | component1 = Albireo B
 | radial_v = −18.80<ref name=ascc/>
 | prop_mo_ra = −1.078<ref name="DR3-2"/>
 | prop_mo_dec = −1.540<ref name="DR3-2"/>
 | parallax = 8.1896
 | p_error = 0.0781
 | parallax_footnote = <ref name="DR3-2">{{Cite Gaia DR3|2026113339752723456}}</ref>
 | dist_ly = {{val|395.4|2.9|3.3}}
 | dist_pc = {{val|121.3|0.9|1}}
 | dist_footnote = <ref name="b-j"/>
}}
{{Starbox relpos
| epoch = 2006
| primary = Albireo A
| component = Albireo B
| angdistsec = 35.3
| angdistref = <ref name=wdsb />
| posang = 54
| posangref = <ref name=wdsb />
}}
{{Starbox orbit
| reference = <ref name=drimmel2021/>
| primary = Aa
| name = Ac
| period = {{val|121.65|3.34|2.90}}
| axis = {{val|0.401|0.007|0.006}}
| eccentricity = {{val|0.20|0.01|0.02}}
| inclination = {{val|156.15|2.90|2.63}}
| node = {{val|84.43|5.27|4.50}}
| periastron = B2026.36
| periarg = {{val|54.72|1.88|2.24}}
| k1 = {{val|2.91|0.09|0.12}}
}}
{{Starbox detail
| component1 = Albireo Aa
| mass = 5.2<ref name=drimmel2021/>
| radius = {{val|58.69|2.83|3.12}}<ref name="npoi"/>
| luminosity_bolometric = 1,259<ref name=drimmel2021/>
| temperature = 4,383<ref name=drimmel2021/>
| rotational_velocity = 8.34<ref name=drimmel2021/>
| gravity = 0.93<ref name=drimmel2021/>
| metal_fe = −0.1<ref name=lefevre/>
}}
{{Starbox detail|no_heading=y
| component1 = Albireo Ac
| mass = 2.7<ref name=drimmel2021/>
| radius = 3.0{{efn|name=radius2}}
| temperature = 10,000<ref name=drimmel2021/>
| luminosity_bolometric = 79<ref name=drimmel2021/>
| component2             = Albireo Ad
| mass2                   = 0.085 ± 0.007<ref name="Albireo Ad" />
}}
{{Starbox detail|no_heading=y
| component1             = Albireo B
| mass                   = 3.7 ± 0.8<ref name=physparms />
| radius                 = 2.59<ref name=fracassini/>
| luminosity_bolometric  = 230 ± 90<ref name=physparms />
| gravity                = 4.00 ± 0.15<ref name=physparms />
| temperature            = 13,200 ± 600<ref name=physparms />
| age_myr                = 100<ref name=physparms />
}}
{{Starbox catalog
| names = [[Bayer designation|β&nbsp;Cygni]], [[Flamsteed designation|6&nbsp;Cygni]], [[Aitken Double Star Catalogue|ADS]]&nbsp;12540, [[Catalogue of Components of Double and Multiple Stars|CCDM]]&nbsp;J19307+2758, [[Washington Double Star Catalog|WDS]]&nbsp;19307+2758<ref name=simbada /><ref name=wdsa /><ref name=pisco />
 | component2 = Albireo A
 | names2     = β¹&nbsp;Cygni, [[Bonner Durchmusterung|BD]]+27&nbsp;3410, [[Bright Star Catalogue|HR]]&nbsp;7417, [[Henry Draper Catalogue|HD]]&nbsp;183912/183913, [[Hipparcos Catalogue|HIP]]&nbsp;95947, [[Smithsonian Astrophysical Observatory Star Catalogue|SAO]]&nbsp;87301, [[Catalogues of Fundamental Stars|FK5]]&nbsp;732, [[Double star designation|MCA]]&nbsp;55&nbsp;Aac, NSV&nbsp;12105
 | component3 = Albireo B
 | names3     = β²&nbsp;Cygni, [[Double star designation|STF&nbsp;4043B]], [[Bonner Durchmusterung|BD]]+27&nbsp;3411,
[[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<ref name=simbadb />
}}
{{Starbox reference
| Simbad = STF+4043 |sn=β Cyg (STF 4043)
| Simbad2 = Albireo |sn2=Albireo A
| Simbad3 = HD+183912 |sn3=Albireo Aa
| Simbad4 = HD+183913 |sn4=Albireo Ab
| Simbad5 = HD+183914 |sn5=Albireo B
}}
{{Starbox end}}

'''Albireo''' {{IPAc-en|æ|l|'|b|ɪr|i|ou}}<!--and yes, the 'e' is short in Latin, so the stress is on the ante-penult--><ref name=Kunitzsch/> is a [[binary star]] designated '''Beta Cygni''' ('''β Cygni''', abbreviated '''Beta Cyg''', '''β Cyg'''). The [[International Astronomical Union]] uses the name "Albireo" specifically for the brightest star in the system.<ref name="IAU-CSN"/> Although designated '[[beta]]', it is fainter than [[Gamma Cygni]], [[Delta Cygni]], and [[Epsilon Cygni]] and is the [[List of stars in Cygnus|fifth-brightest point of light]] in the [[constellation]] of [[Cygnus (constellation)|Cygnus]]. Appearing to the naked eye to be a single star of [[Apparent magnitude|magnitude]] 3, viewing through even a low-magnification [[telescope]] resolves it into its two components. The brighter yellow star, itself a very close [[star system|trinary system]], makes a striking colour contrast with its fainter blue companion.<ref name=stars/>

==Nomenclature==

[[File:CygnusCC.jpg|thumb|left|upright|Albireo is the star in the head of the constellation of Cygnus (bottom).]]

''β Cygni'' ([[Latinisation of names|Latinised]] to ''Beta Cygni'') is the system's [[Bayer designation]]. The brighter of the two components is designated ''β¹ Cygni'' or ''Beta Cygni A'' and the fainter ''β² Cygni'' or ''Beta Cygni B''.

The origin of the star system's traditional name ''Albireo'' is unclear. [[Christian Ludwig Ideler]] traced it to [https://viewer.slv.vic.gov.au/?entity=IE10167306&file=FL21840507&mode=browse the heading for the constellation we call Cygnus] in Ptolemy's star catalog, in the translation of the [[Almagest]] by [[Gerard of Cremona]]: "''Stellatio Eurisim: et est volans; et jam vocatur gallina. et dicitur eurisim quasi redolens ut lilium ab ireo''" ("Constellation Eurisim: and it is the Flyer, and it is also called the Hen, and it is called Eurisim as if redolent like the lily from the 'ireo'"). (The original Greek just calls the constellation "Ορνιθος αστερισμος", "the constellation of the Bird".) The word "ireo" is obscure as well{{snd}}Ideler suggests that Gerard took "Eurisim" to mean the plant ''[[Erysimum]]'', which is called ''[[wikt:irio|irio]]'' in Latin, but the ablative case of that is not "ireo" but ''irione''.<ref>p. 24, [https://archive.org/details/namesstarsandco00higggoog/page/n27/mode/2up ''The names of the stars and constellations compiled from the Latin, Greek and Arabic''], W. H. Higgins, Leicester: Samuel Clarke, 1882.</ref> In any case, Ideler proposed that (somehow) the phrase "ab ireo" was applied to the star at the head of the bird, and this became "Albireo" when an "l" was mistakenly inserted as though it was an Arabic name.<ref>{{Cite web|url=https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Cygnus*.html|title=LacusCurtius • Allen's Star Names — Cygnus}} Allen quotes (in translation) a passage from Ideler's ''Untersuchungen über den Ursprung und die Bedeutung der Sternnamen'' (1809), [https://archive.org/details/untersuchungenb01idelgoog/page/n115/mode/2up page 75].</ref> Ideler also supposed that the name Eurisim was a mistaken transliteration of the Arabic name "Urnis" for Cygnus (from the Greek "Ορνις").

In 2016, the [[International Astronomical Union]] (IAU) organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name="WGSN"/> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1"/> included a table of the first two batches of names approved by the WGSN; which included ''Albireo '' for β¹ Cygni. It is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN"/>

Medieval Arabic-speaking astronomers called Beta Cygni ''{{Transliteration|ar|minqār al-dajāja<sup>h</sup>}}'' (English: ''the hen's beak'').<ref>p. 196, [https://archive.org/details/bub_gb_5xQuAAAAIAAJ ''Star-names and Their Meanings''], Richard Hinckley Allen, New York, G. E. Stechert, 1899.</ref> The term ''{{Transliteration|ar|minqār al-dajāja<sup>h</sup>}}'' (منقار الدجاجة) or ''Menchir al Dedjadjet'' appeared in the catalogue of stars in the ''Calendarium of Al Achsasi Al Mouakket'', which was translated into [[Latin]] as ''Rostrum Gallinae'', meaning ''the hen's beak''.<ref name=knobel1895/>

Since Cygnus is the swan, and Beta Cygni is located at the head of the swan, it is sometimes called the "beak star".<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>  With [[Deneb]], [[Gamma Cygni]] (Sadr), [[Delta Cygni]], and [[Epsilon Cygni]] (Gienah), it forms the [[Asterism (astronomy)|asterism]] called the [[Northern Cross (asterism)|Northern Cross]].<ref name=darling/>

==Properties==
[[File:NewAlbireo.jpg|thumb|left|Albireo A and B]]
Beta Cygni is about {{convert|420|ly|pc|0|lk=on}} away from the [[Sun]].<ref name=drimmel2021/> When viewed with the naked eye, Albireo appears to be a single star. However, in a [[telescope]] it resolves into a [[double star]] consisting of β Cygni A (amber, [[apparent magnitude]] 3.1), and β Cygni B (blue-green, apparent magnitude 5.1).<ref name=msg /> Separated by 35 seconds of arc,<ref name=wdsb>Entry, [https://archive.today/20000819072800/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> the two components provide one of the best contrasting double stars in the sky due to their different colors.

It is not known whether the two components β Cygni A and B are orbiting around each other in a physical [[binary star|binary system]], or if they are merely an [[double star|optical double]].<ref name=drimmel2021/> If they are a physical binary, their orbital period is probably at least 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> Some experts, however, support the optical double argument, based on observations that suggest different [[proper motion]]s for the components, which implies that they are unrelated.<ref name="SkyTel1"/> The primary and secondary also have different measured distances from the [[Hipparcos]] mission – {{convert|133 ± 6|pc|ly|lk=on|order=flip}} for the primary and {{convert|123 ± 4|pc|ly|lk=on|order=flip}} for the secondary.<ref name=hipparcos/> More recently the [[Gaia (spacecraft)|Gaia]] mission has measured distances of about 330–390 light years (100–120 parsecs) for both components, but noise in the astrometric measurements for the stars means that data from Gaia's second data release is not yet sufficient to determine whether the stars are physically associated.<ref name=dr2distances/>

In around 3.87 million years, Albireo will become [[historical brightest stars|the brightest star]] in the night sky.<ref name=tomkin1998>{{cite journal|last=Tomkin|first=Jocelyn|date=April 1998|title=Once and Future Celestial Kings|journal=Sky and Telescope|volume=95|issue=4|pages=59–63|bibcode=1998S&T....95d..59T}} – based on computations from [[HIPPARCOS]] data. (The calculations exclude stars whose distance or [[proper motion]] is uncertain.) [ftp://tlgleonid.asuscomm.com/HITACHI/BOOK_ASTRO/S&T/SkyandTelescope_1998%20-%20astronomy/04/199804059063.pdf PDF]{{dead link|date=November 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> It will peak in brightness with an apparent magnitude of –0.53 in 4.61 million years.<ref name=tomkin1998 />

There are a further 10 faint companions listed in the Washington Double Star catalogue, all fainter than magnitude 10. Only one is closer to the primary than Albireo B, with the others up to 142" away.<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] {{Webarchive|url=https://web.archive.org/web/20171112062424/http://ad.usno.navy.mil/wds/orb6/orb6frames.html |date=2017-11-12 }},  William I. Hartkopf & Brian D. Mason, U.S. Naval Observatory.  Accessed on line July 9, 2008. [http://ad.usno.navy.mil/wds/orb6/orb6orbits.html#19307+2758 (19307+2758)] {{Webarchive|url=https://web.archive.org/web/20110517115734/http://ad.usno.navy.mil/wds/orb6/orb6orbits.html#19307+2758 |date=2011-05-17 }}</ref>

===Albireo A===
The [[stellar spectrum|spectrum]] of Beta Cygni A was found to be composite when it was observed as part of the [[Henry Draper]] Memorial project in the late 19th century, leading to the supposition that it was itself double.<ref name=maury1897/> This was supported by observations from 1898 to 1918 which showed that it had a varying [[radial velocity]].<ref name=campbell1919/> In 1923, the two components were identified in the [[Henry Draper Catalogue]] as HD 183912 and HD 183913.<ref name=freestarcharts/><ref name=hd/>

In 1978, speckle interferometry observations using the 1.93m telescope at the [[Haute-Provence Observatory]] resolved a companion at 0.125". This observation was published in 1980,<ref name=bonneau/> and the companion is referred to as component Ab in the [[Washington Double Star Catalog]].<ref name=wdsa/>

In 1976 [[speckle interferometry]] was used to resolve a companion using the 2.1-meter telescope at the [[Kitt Peak National Observatory]]. It was measured at a separation of 0.44", and it is noted that the observation was inconsistent with the Haute-Provence observations and hence not of the same star.<ref name=pisco/><ref name=mcalister1982/> Although these observations pre-dated those at Haute-Provence, they were not published until 1982 and this component is designated Ac in the Washington Double Star Catalog.<ref name=wdsa/> It is designated as component C in the [[Catalog of Components of Double and Multiple Stars]],<ref name=ccdm/> not to be confused with component C in the Washington Double Star Catalog which is a faint optical companion.<ref name=wdsa/> An orbit for the pair has since been computed using interferometric measurements, but as only approximately a quarter of the orbit has been observed, the orbital parameters must be regarded as preliminary. The period of this orbit is 214 years.<ref name=pisco/>  The confirmed close pair are referred to as Aa and Ac in modern papers, with Ab being the unconfirmed third component.<ref name=drimmel2021/> A 2022 study treats the existence of Albireo Ab as "very unlikely".<ref name="Albireo Ad"/>

In 2022, a third component was found to be orbiting Albireo Aa, named Albireo Ad. It is a very-low-mass star with around 8.5% the Sun's mass and an orbital period of 371 days.<ref name="Albireo Ad">{{Cite journal |last1=Jack |first1=D. |last2=Schröder |first2=K.-P. |last3=Mittag |first3=M. |last4=Bastian |first4=U. |date=2022-05-01 |title=Yet another star in the Albireo system - The discovery of Albireo Ad |url=https://www.aanda.org/articles/aa/full_html/2022/05/aa43255-22/aa43255-22.html |journal=Astronomy & Astrophysics |language=en |volume=661 |pages=A49 |doi=10.1051/0004-6361/202243255 |issn=0004-6361|arxiv=2203.04222 |bibcode=2022A&A...661A..49J }}</ref>

The diameter of the primary K-type giant star has been measured using [[interferometry]] from the [[Navy Precision Optical Interferometer]]. A [[Limb darkening|limb-darkened]] angular diameter of {{val|4.904|ul=mas}} was measured. At the [[parallax]]-derived distance of 111.4{{nbsp}}pc, a radius equivalent to {{solar radius|58.69|link=y}} is calculated.<ref name="npoi">{{Citation|last1=Baines |first1=Ellyn K. |last2=Clark |first2=James H., III |last3=Schmitt |first3=Henrique R. |last4=Stone |first4=Jordan M. |last5=von Braun |first5=Kaspar |date=2023-12-01 |title=33 New Stellar Angular Diameters from the NPOI, and Nearly 180 NPOI Diameters as an Ensemble |journal=The Astronomical Journal |volume=166 |issue=6 |pages=268 |doi=10.3847/1538-3881/ad08be |doi-access=free |bibcode=2023AJ....166..268B |issn=0004-6256}}</ref>

===Albireo B===
β Cygni B is a fast-rotating [[Be star]], with an equatorial rotational velocity of at least 250 kilometers per second.<ref name="stars"/>  Its surface temperature has been [[spectroscopy|spectroscopically]] estimated to be about 13,200 [[Kelvin|K]].<ref name=physparms/>

β Cygni B has been reported to be a very close double,<ref name=roberts/> but the observations appear to have been incorrect.<ref name=wdsa/>

==Moving group==
Analysis of [[Gaia Data Release 2]] astrometry suggests that four fainter stars may form a [[moving group]] along with the brighter visible components.<ref name=drimmel2021/>

==Namesakes==
[[USS Albireo (AK-90)|''Albireo'' (AK-90)]] was a [[United States Navy]] [[Crater-class cargo ship|''Crater''-class cargo ship]] named after the star.

==Notes==
{{notelist|refs=

{{efn | name=radius2 | Applying the [[Stefan-Boltzmann Law]] with a nominal [[sun|solar]] [[effective temperature]] of 5,772&nbsp;[[Kelvin|K]]: 
:<math>\sqrt{(5772/10000)^4 * 79} = 2.96\ R\odot</math>}}

}}

==References==
{{Reflist|refs=

<ref name=tycho2>{{cite journal|bibcode=2000A&A...355L..27H|title=The Tycho-2 catalogue of the 2.5 million brightest stars|journal=Astronomy and Astrophysics|volume=355|pages=L27|last1=Høg|first1=E|last2=Fabricius|first2=C|last3=Makarov|first3=V. V|last4=Urban|first4=S|last5=Corbin|first5=T|last6=Wycoff|first6=G|last7=Bastian|first7=U|last8=Schwekendiek|first8=P|last9=Wicenec|first9=A|year=2000}}</ref>

<ref name=tycho>{{cite journal|bibcode=2002A&A...384..180F|title=The Tycho double star catalogue|journal=Astronomy and Astrophysics|volume=384|pages=180–189|last1=Fabricius|first1=C|last2=Høg|first2=E|last3=Makarov|first3=V. V|last4=Mason|first4=B. D|last5=Wycoff|first5=G. L|last6=Urban|first6=S. E|year=2002|doi=10.1051/0004-6361:20011822|doi-access=free}}</ref>

<ref name=simbadb>{{SIMBAD link|HD+183914|HD 183914 -- Emission-line Star}}, database entry, [[SIMBAD]].  Accessed on line July 9, 2008.</ref>

<ref name=edr3B>{{cite Gaia EDR3|2026113339752723456}}</ref>

<ref name=bsd>{{cite journal|bibcode=2000AJ....119.2403T|title=Binary Star Differential Photometry Using the Adaptive Optics System at Mount Wilson Observatory|journal=The Astronomical Journal|volume=119|issue=5|pages=2403|last1=Ten Brummelaar|first1=Theo|last2=Mason|first2=Brian D|last3=McAlister|first3=Harold A|last4=Roberts|first4=Lewis C|last5=Turner|first5=Nils H|last6=Hartkopf|first6=William I|last7=Bagnuolo|first7=William G|year=2000|doi=10.1086/301338|doi-access=free}}.  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>

<ref name=photometry>{{cite journal|bibcode=2002yCat.2237....0D|title=VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system|journal=CDS/ADC Collection of Electronic Catalogues|volume=2237|last1=Ducati|first1=J. R|year=2002}}</ref>

<ref name=levenhagen>{{cite journal|bibcode=2006MNRAS.371..252L|arxiv=astro-ph/0606149|title=Spectroscopic analysis of southern B and Be stars|journal=Monthly Notices of the Royal Astronomical Society|volume=371|issue=1|pages=252–262|last1=Levenhagen|first1=R. S|last2=Leister|first2=N. V|year=2006|doi=10.1111/j.1365-2966.2006.10655.x|doi-access=free |s2cid=16492030}}</ref>

<ref name=simbada>{{SIMBAD link|NAME+ALBIREO|NAME ALBIREO -- Star in double system }}, database entry, [[SIMBAD]].  Accessed on line July 9, 2008.</ref>

<ref name=ascc>{{cite journal|bibcode= 2007AN....328..889K |title= Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ˜55000 stars and mean radial velocities of 516 Galactic open clusters and associations |journal= Astronomische Nachrichten |volume= 328 |issue= 9 |pages= 889 |last1= Kharchenko |first1= N. V |last2= Scholz |first2= R.-D |last3= Piskunov |first3= A. E |last4= Röser |first4= S |last5= Schilbach |first5= E |year= 2007 |doi= 10.1002/asna.200710776 |arxiv= 0705.0878 |s2cid= 119323941 }}</ref>

<ref name=lefevre>{{cite journal|bibcode=2006A&A...450.1173L|title=Lithium abundances and rotational behavior for bright giant stars|journal=Astronomy and Astrophysics|volume=450|issue=3|pages=1173|last1=Lèbre|first1=A.|last2=De Laverny|first2=P.|last3=Do Nascimento|first3=J. D.|last4=De Medeiros|first4=J. R.|year=2006|doi=10.1051/0004-6361:20053485|doi-access=free}}</ref>

<ref name=fracassini>{{cite journal|bibcode=1973Ap&SS..22..141F|title=Apparent diameters of 172 B5V-A5V stars of the Catalogue of Geneva Observatory|journal=Astrophysics and Space Science|volume=22|issue=1|pages=141–152|last1=Fracassini|first1=Massimo|last2=Gilardoni|first2=Giorgio|last3=Pasinetti|first3=Laura E.|year=1973|doi=10.1007/BF00642829|s2cid=120496963}}</ref>

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<ref name=stars>{{cite web|url=http://stars.astro.illinois.edu/sow/albireo.html|title=Albireo|author=Jim Kaler|access-date=2018-01-07}}</ref>

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<ref name="SkyTel1">{{cite news 
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<ref name=physparms>Table 1, {{cite journal | doi = 10.1086/381063 | bibcode = 2004AJ....127.1176L | volume=127 | title=Physical Parameters of Southern B- and Be-Type Stars | year=2004 | journal=The Astronomical Journal | pages=1176–1180 | last1 = Levenhagen | first1 = R. S.| issue = 2 | s2cid = 121487369 }}</ref>

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}}

==Further reading==
*{{cite journal|bibcode=1980S&T....59..210W|title=Albireo as a Triple Star|journal=Sky and Telescope|volume=59|pages=210|last1=Webb|first1=T. W.|last2=McAlister|first2=H. A.|last3=Worley|first3=C. E.|last4=Burnham|first4=S. W.|last5=Aitken|first5=R. G.|year=1980}}

==External links==
{{Commons}}
* {{APOD |date=30 August 2005 |title=Albireo: A Bright and Beautiful Double}}
* [http://www.photomeeting.de/astromeeting/double/050728betCYGa1024.htm A picture of Albireo by Stefan Seip] ({{Webarchive|url=https://web.archive.org/web/20070927185356/http://www.photomeeting.de/astromeeting/double/050728betCYGa1024.htm |date=2007-09-27 }})
* [http://fuzzyblobsmk.blogspot.co.uk/2011/08/famous-summer-double.html Albireo] at Pete Roberts' Fuzzy Blobs site
* [https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Cygnus*.html About Cygnus], including more information about the origin of the name Albireo.

{{Stars of Cygnus}}
{{Portal bar|Astronomy|Stars|Outer space}}

[[Category:B-type main-sequence stars]]
[[Category:Bayer objects|Cygni, Beta]]
[[Category:Be stars]]
[[Category:Binary stars]]
[[Category:Bright Star Catalogue objects|7417]]
[[Category:Cygnus (constellation)]]
[[Category:Durchmusterung objects|BD+27 3410]]
[[Category:Flamsteed objects|Cygni, 06]]
[[Category:Henry Draper Catalogue objects|183912]]
[[Category:Hipparcos objects|095947]]
[[Category:K-type bright giants]]
[[Category:Stars with proper names|Albireo]]
[[Category:Triple stars]]