View source for Arcturus

{{Short description|Brightest star in the constellation Boötes}}
{{hatnote group|
{{other uses}}
{{redirect|α Boötis|A Boötis|HD 125351}}
}}
{{Use mdy dates|date=January 2025}}
{{Starbox begin}}
{{Starbox image
| image =
   {{Location mark
 | image=Boötes_IAU.svg
 | float=center | width=250 | position=right
 | mark=Red circle.svg | mark_width=14 | mark_link=α Boo
 | x%=56.2 | y%=62.8
   }}
| caption=Arcturus in the constellation of Boötes (circled)
}}
{{Starbox observe
 | epoch       =J2000
 | constell    =[[Boötes]]
 | pronounce   ={{IPAc-en|ɑːr|k|ˈ|tj|ʊər|ə|s|audio=LL-Q1860 (eng)-Naomi Persephone Amethyst (NaomiAmethyst)-Arcturus.wav}}
 | ra          ={{RA|14|15|39.7}}<ref name="vanLeeuwen2007"/>
 | dec         ={{DEC|+19|10|56}}<ref name="vanLeeuwen2007"/>
 | appmag_v    =−0.05<ref name=ducati/>
}}
{{Starbox character
 | class             = K1.5 III Fe−0.5<ref name=perkins/>
 | appmag_1_passband = [[J band (infrared)|J]]
 | appmag_1          = −2.25<ref name=ducati/>
 | b-v               = +1.23<ref name=ducati/>
 | u-b               = +1.28<ref name=ducati/>
 | r-i               = +0.65<ref name=ducati/>
 | v-r               =
 | variable          =
 | type              = [[Red giant branch]]<ref name=ramirez_prieto_2011/>
}}
|- bgcolor="#FFFAFA"
| Note (category: variability): || H and K emission vary.
{{Starbox astrometry
 | radial_v          =−5.19<ref name=massarotti2008/>
 | prop_mo_ra        ={{val|-1093.45}}<ref name=Perryman1997/>
 | prop_mo_dec       ={{val|-1999.40}}<ref name=Perryman1997/>
 | parallax          =88.83
 | p_error           =0.54
 | parallax_footnote =<ref name="vanLeeuwen2007"/>
 | absmag_v          ={{val|-0.30|0.02}}<ref name=aj135_3_892/>
}}
{{Starbox detail
 | mass                ={{val|1.08|0.06}}<ref name=ramirez_prieto_2011/>
 | metal_fe            ={{val|-0.52|0.04}}<ref name=ramirez_prieto_2011/>
 | radius              ={{val|25.4|0.2}}<ref name=ramirez_prieto_2011/>
 | rotational_velocity ={{val|2.4|1.0}}<ref name=aj135_3_892/>
 | luminosity          =170<ref name=aaa465_2_593/>
 | temperature         ={{val|4286|30|fmt=commas}}<ref name=ramirez_prieto_2011/>
 | gravity             ={{val|1.66|0.05}}<ref name=ramirez_prieto_2011/>
 | age_gyr             ={{val|7.1|+1.5|-1.2}}<ref name=ramirez_prieto_2011/>
}}
{{Starbox catalog
 | names={{odlist | name=Alramech | name2=Aramech | name3=Abramech | B=α&nbsp;Boötis, Alpha&nbsp;Boo, α&nbsp;Boo | F=16 Boötis | BD=+19°2777 | GJ=541 | HD=124897 | HIP=69673 | HR=5340 | SAO=100944 | GCTP=3242.00 | LHS=48 }}, [[General Catalogue of Trigonometric Parallaxes|GCTP]]&nbsp;3242.00
}}
{{Starbox reference
 | Simbad=HD+124897
 | ARICNS =
}}
{{starbox sources|HIP|CCDM|HR|[http://webviz.u-strasbg.fr/viz-bin/VizieR-S?HR%205340 VizieR catalog entry]}}
{{Starbox end}}

'''Arcturus''' is a [[red giant]] star in the [[Northern celestial hemisphere|northern]] [[constellation]] of [[Boötes]], and the brightest star in the constellation. It has the [[Bayer designation]] '''α Boötis''', which is [[Latinisation of names|Latinized]] to '''Alpha Boötis''' and abbreviated '''Alf Boo''' or '''α Boo'''. With an [[apparent visual magnitude]] of −0.05,<ref name=ducati/> it is the [[List of brightest stars|fourth-brightest]] star in the [[night sky]] and the brightest in the [[northern celestial hemisphere]]. Arcturus forms one corner of the [[Spring Triangle]] [[Asterism (astronomy)|asterism]].

Located relatively close at 36.7 [[light-year]]s from the [[Sun]], Arcturus is a [[red giant]] of [[Stellar classification|spectral type]] K1.5III—an aging star around 7.1 billion years old that has used up its [[Stellar core|core]] [[hydrogen]] and [[stellar evolution|evolved]] off the [[main sequence]]. It is about the same mass [[Solar mass|as the Sun]], but has expanded to 25 times [[Solar radius|its size]] (around 35 million kilometers) and is around 170 times as luminous.

==Nomenclature==
The traditional name ''Arcturus'' is Latinised from the [[ancient Greek]] ''Ἀρκτοῦρος'' (Arktouros) and means "Guardian of the Bear",<ref>{{cite web|url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3D*%29arktou%3Dros |title=Ἀρκτοῦρος | first1=Henry George | last1=Liddell | first2=Robert | last2=Scott | work=A Greek-English Lexicon | access-date=2019-01-16}}</ref> ultimately from ''ἄρκτος'' (''arktos''), "bear"<ref>{{cite web|url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Da%29%2Frktos |title=ἄρκτος | first1=Henry George | last1=Liddell | first2=Robert | last2=Scott | work=A Greek-English Lexicon | access-date=2019-01-16}}</ref> and ''οὖρος'' (ouros), "watcher, guardian".<ref>{{cite web|url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dou%29%3Dros2 |title=οὖρος | first1=Henry George | last1=Liddell | first2=Robert | last2=Scott |work=A Greek-English Lexicon| access-date=2019-01-16}}</ref> As ''ἄρκτος'' also came to mean "north", the name can also translate to "Guardian of the North".<ref name="IAU-CSN-new">{{cite web |title=IAU Catalog of Star Names |url=https://exopla.net/star-names/modern-iau-star-names/ |access-date=25 May 2025}}</ref> 

The [[Bayer designation|designation]] of Arcturus as ''α Boötis'' ([[Latinisation of names|Latinised]] to ''Alpha Boötis'') was made by [[Johann Bayer]] in 1603. In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included ''Arcturus'' for α Boötis.<ref name="WGSN1" /><ref name="IAU-CSN" />

==Observational history==
Arcturus and its distinctive red color have been mentioned since [[classical antiquity|antiquity]] and [[medieval times]]; [[Ptolemy]] described it as ''subrufa'' ("slightly red"),<ref name=acgf/> and [[Geoffrey Chaucer]] referred to it as ''Alramih'' in ''[[A Treatise on the Astrolabe]]'' (1391).<ref name=chaucerlabe/>

In 1635, the French mathematician and astronomer [[Jean-Baptiste Morin (mathematician)|Jean-Baptiste Morin]] observed Arcturus in the daytime with a telescope. This was the first recorded full daylight viewing for any star other than the [[Sun]] and [[supernova]]e.<ref name=guide/>

==Observation==
[[File:BootesCC.jpg|thumb|left|upright|Arcturus is the brightest star in the constellation of [[Boötes]].]]

With an [[apparent visual magnitude]] of&nbsp;−0.05, Arcturus is the brightest star in the [[northern celestial hemisphere]] and the [[list of brightest stars|fourth-brightest star]] in the night sky,<ref name=100greatest/> after [[Sirius]] (−1.46&nbsp;apparent magnitude), [[Canopus (star)|Canopus]] (−0.72) and [[α Centauri]] (combined magnitude of −0.27). However, α Centauri AB is a [[binary star]], whose components are each fainter than Arcturus. This makes Arcturus the third-brightest individual star, just ahead of α Centauri&nbsp;A (officially named ''Rigil Kentaurus''), whose apparent magnitude {{nobr|is −0.01}}.<ref name=schaaf/> Arcturus has been seen at or just before sunset with the naked eye.<ref name=schaaf/>

Arcturus is visible from both of [[Earth]]'s hemispheres as it is located 19° north of the [[celestial equator]]. The star [[culmination|culminates]] at midnight on April 27, and at 9 p.m. on June 10 being visible during the late northern spring or the southern autumn.<ref>Schaaf, p. 257.</ref> From the [[Northern Hemisphere]], an easy way to find Arcturus is to follow the arc of the handle of the [[Big Dipper]] (or Plough in the [[United Kingdom|UK]]). By continuing in this path, one can find [[Spica]], "Arc to Arcturus, then spike (or speed on) to Spica".<ref name=rao2007/><ref name=earthsky/> Together with the bright stars [[Spica]] and [[Regulus]] (or [[Denebola]], depending on the source), Arcturus is part of the [[Spring Triangle]] [[Asterism (astronomy)|asterism]]. With [[Cor Caroli]], these four stars form the [[Great Diamond]] asterism.

Arcturus has a B-V color index of +1.23, roughly midway between [[Pollux (star)|Pollux]] (B-V +1.00) and [[Aldebaran]] (B-V +1.54).<ref name=schaaf/>

[[η Boötis]], or Muphrid, is only 3.3 [[light-year]]s distant from Arcturus, and would have a visual magnitude −2.5, about as bright as [[Jupiter]] at its brightest from Earth, whereas an observer on the former system would find Arcturus with a magnitude -5.0, slightly brighter than [[Venus]] as seen from Earth, but with an orangish color.<ref name=schaaf/>

==Physical characteristics==
[[File:Arcturus (optical).png|thumb|right|Optical image of Arcturus (DSS2 / MAST / STScI / NASA)]]
Based upon an annual [[stellar parallax|parallax]] shift of 88.83&nbsp;[[Minute and second of arc#Astronomy|milliarcseconds]], as measured by the [[Hipparcos]] satellite, Arcturus is {{Convert|11.26|pc|ly|abbr=off|lk=on|order=flip}} from Earth. The parallax [[margin of error]] is 0.54 milliarcseconds, translating to a distance margin of error of ±{{Convert|0.069|pc|ly|abbr=off|order=flip}}.<ref name="vanLeeuwen2007"/> Because of its proximity, Arcturus has a high [[proper motion]], two [[Minute and second of arc#Astronomy|arcseconds]] a year, greater than any [[first magnitude star]] other than α&nbsp;Centauri. It is [[list of nearest giant stars|the second-closest giant star]] to Earth, after [[Pollux (star)|Pollux]].

Arcturus is moving rapidly ({{cvt|122|km/s|mph|disp=or||}}) relative to the Sun, and is now almost at its closest point to the Sun. Closest approach will happen in about 4,000 years, when the star will be a few hundredths of a light-year closer to Earth than it is today. (In antiquity, Arcturus was closer to the centre of the constellation.<ref name=rogers982/>) Arcturus is thought to be an [[old-disk star]],<ref name=ramirez_prieto_2011/> and appears to be moving with a group of 52 other such stars, known as the [[Arcturus stream]].<ref name=ramya/>

With an [[absolute magnitude]] of −0.30, Arcturus is, together with [[Vega]] and Sirius, one of the most luminous stars in the Sun's neighborhood. It is about 110 times brighter than the Sun in visible light wavelengths, but this underestimates its strength as much of the light it gives off is in the [[infrared]]; total ([[Bolometric correction|bolometric]]) power output is about 180&nbsp;times that of the Sun. With a near-infrared [[J band (infrared)|J band]] [[Magnitude (astronomy)|magnitude]] of −2.2, only [[Betelgeuse]] (−2.9) and [[R Doradus]] (−2.6) are brighter. The lower output in visible light is due to a lower [[Luminous efficacy|efficacy]] as the star has a lower [[effective temperature|surface temperature]] than the Sun.

There have been suggestions that Arcturus might be a member of a binary system with a faint, cool companion, but no companion has been directly detected.<ref name=ramirez_prieto_2011/>
In the absence of a binary companion, the mass of Arcturus cannot be measured directly, but models suggest it is slightly greater than that of the Sun. Evolutionary matching to the observed physical parameters gives a mass of {{Val|1.08|0.06|u=solar mass}},<ref name=ramirez_prieto_2011/> while the oxygen isotope ratio for a first [[dredge-up]] star gives a mass of {{solar mass|1.2}}.<ref name=abia/> The star, given its evolutionary state, is expected to have undergone significant mass loss in the past.<ref name=Lagarde_et_al_2015/> The star displays [[Stellar magnetic field|magnetic activity]] that is heating the [[stellar corona|coronal]] structures, and it undergoes a [[Solar cycle|solar-type magnetic cycle]] with a duration that is probably less than 14 years. A weak magnetic field has been detected in the [[photosphere]] with a strength of around half a [[Gauss (unit)|gauss]]. The magnetic activity appears to lie along four latitudes and is rotationally modulated.<ref name=Sennhauser2011/>

Arcturus is estimated to be around 6 to 8.5 billion years old,<ref name=ramirez_prieto_2011/> but there is some uncertainty about its evolutionary status.<ref name=Pavlenko2008/> Based upon the [[Color index|color characteristics]] of Arcturus, it is currently ascending the [[red-giant branch]] and will continue to do so until it accumulates a large enough degenerate helium [[Stellar core|core]] to ignite the [[helium flash]].<ref name=ramirez_prieto_2011/> It has likely exhausted the [[hydrogen]] from its core and is now in its active [[red giant|hydrogen shell burning]] phase. However, Charbonnel et al. (1998) placed it slightly above the [[horizontal branch]], and suggested it has already completed the helium flash stage.<ref name=Pavlenko2008/>
[[File:Sun to Arcturus comparison.jpg|thumb|Size comparison between the [[Sun]], [[Beta Ursae Majoris]], [[Pollux (star)|Pollux]], and Arcturus.]]

===Spectrum===
Arcturus has [[stellar evolution|evolved]] off the main sequence to the [[red giant branch]], reaching an [[early-type star|early]] [[k-type star|K-type]] [[stellar classification]]. It is frequently assigned the spectral type of K0III,<ref name=gray/> but in 1989 was used as the spectral standard for type K1.5III Fe−0.5,<ref name=perkins/> with the suffix notation indicating a mild underabundance of iron compared to typical stars of its type. As the brightest K-type [[Giant star#Red giants|giant]] in the sky, it has been the subject of multiple [[spectral atlas|atlases]] with coverage from the [[ultraviolet]] to [[infrared]].<ref name=griffin1968/><ref name=hinckle2005/>

The spectrum shows a dramatic transition from [[emission line]]s in the ultraviolet to atomic [[absorption line]]s in the visible range and molecular absorption lines in the infrared. This is due to the optical depth of the atmosphere varying with wavelength.<ref name=hinckle2005/> The spectrum shows very strong absorption in some molecular lines that are not produced in the [[photosphere]] but in a surrounding shell.<ref name=tsuji2009/> Examination of [[carbon monoxide]] lines show the molecular component of the atmosphere extending outward to 2–3 times the radius of the star, with the [[stellar wind|chromospheric wind]] steeply accelerating to 35–40&nbsp;km/s in this region.<ref name="Ohnaka_Morales_Marín_2018"/>

Astronomers term "metals" those elements with higher [[atomic number]]s than [[helium]]. The atmosphere of Arcturus has an enrichment of [[alpha elements]] relative to [[iron]] but only about a third of solar [[metallicity]]. Arcturus is possibly a [[Population II star]].<ref name=schaaf/>

===Oscillations===
As one of the brightest stars in the sky, Arcturus has been the subject of a number of studies in the emerging field of [[asteroseismology]]. Belmonte and colleagues carried out a radial velocity (Doppler shift of spectral lines) study of the star in April and May 1988, which showed variability with a frequency of the order of a few [[microhertz]] (μHz), the highest peak corresponding to 4.3&nbsp;μHz (2.7&nbsp;days) with an amplitude of 60 ms<sup>−1</sup>, with a [[frequency separation]] of c.&nbsp;5&nbsp;μHz. They suggested that the most plausible explanation for the variability of Arcturus is stellar oscillations.<ref name=belmonte1990/>

Asteroseismological measurements allow direct calculation of the mass and radius, giving values of {{Val|0.8|0.2|u=solar mass}} and {{Val|27.9|3.4|ul=solar radius}}. This form of modelling is still relatively inaccurate, but a useful check on other models.<ref name=kallinger/>

===Search for planets===
[[Hipparcos]] satellite [[astrometry]] suggested that Arcturus is a [[binary star]], with the companion about twenty times dimmer than the primary and orbiting close enough to be at the very limits of humans' current ability to make it out. Recent results remain inconclusive, but do support the marginal ''Hipparcos'' detection of a binary companion.<ref name=verhoelst2005/>

In 1993, radial velocity measurements of Aldebaran, Arcturus and Pollux showed that Arcturus exhibited a long-period radial velocity oscillation, which could be interpreted as a ''substellar companion''. This [[substellar object]] would be nearly 12&nbsp;times the [[mass of Jupiter]] and be located roughly at the same orbital distance from Arcturus as the Earth is from the Sun, at 1.1&nbsp;[[astronomical unit]]s. However, all three stars surveyed showed similar oscillations yielding similar companion masses, and the authors concluded that the variation was likely to be intrinsic to the star rather than due to the gravitational effect of a companion. So far, no substellar companion has been confirmed.<ref name=Kgiants/>
<!--
{{PlanetboxOrbit begin}}
{{PlanetboxOrbit hypothetical
| exoplanet = [[Arcturus b|b]]
| mass = 11.7
| period = 233
| semimajor = 1.1
| eccentricity = 0.147
}}
{{PlanetboxOrbit end}}
Put the starbox in once a planet has been confirmed, if it is a planet and not a brown dwarf.-->

==Mythology==
[[File:Hugo-de-Groot-Syntagma-Arateorum MG 0605.tif|thumb|Arcturus in Arctophylax, seen between his knees]]
{{See also|Ursa Major#Mythology|Boötes#History and mythology}}
One astronomical tradition associates Arcturus with the mythology around [[Arcas]], who was about to shoot and kill his own mother [[Callisto (mythology)|Callisto]] who had been transformed into a bear. Zeus averted their imminent tragic fate by transforming the boy into the constellation Boötes, called Arctophylax "bear guardian" by the Greeks, and his mother into Ursa Major (Greek: Arctos "the bear"). The account is given in [[Gaius Julius Hyginus|Hyginus]]'s ''[[De Astronomica|Astronomy]]''.<ref name=eratosthenes/>

[[Aratus]] in his ''Phaenomena'' said that the star Arcturus lay below the belt of Arctophylax, and according to [[Ptolemy]] in the ''Almagest'' it lay between his thighs.<ref name=ridpath/>

An alternative lore associates the name with the legend around [[Icarius (Athenian)|Icarius]], who gave the gift of wine to other men, but was murdered by them, because they had had no experience with intoxication and mistook the wine for poison. It is stated that Icarius became Arcturus while his dog, [[Maera (hound)|Maira]], became Canicula ([[Procyon]]), although "Arcturus" here may be used in the sense of the constellation rather than the star.<ref>{{harvp|Eratosthenes|Hyginus|Aratus|Hard (tr.)|2015|pp=38–40}}, p. 182 (note to p. 40)</ref>

==Cultural significance==
As one of the [[List of brightest stars|brightest stars]] in the sky, Arcturus has been significant to observers since antiquity.

In ancient [[Mesopotamia]], it was linked to the god [[Enlil]], and also known as Shudun, "yoke",<ref name=rogers982/> or SHU-PA of unknown derivation in the ''Three Stars Each'' [[Babylonian star catalogues]] and later [[MUL.APIN]] around 1100 BC.<ref name=rogers1998/>

In ancient Greek, the star is found in ancient astronomical literature, e.g. Hesiod's ''Work and Days'', circa 700 BC,<ref name=rogers982/> as well as Hipparchus's and Ptolemy's star catalogs. The folk-etymology connecting the star name with the bears (Greek: ἄρκτος, arktos) was probably invented much later.<ref>{{Cite book |title=Star-names and Their Meanings |publisher=Richard Hinckley Allen |orig-year=1899 |year=2015|isbn=9789333375757 |edition=1st}}</ref> It fell out of use in favour of Arabic names until it was revived in the [[Renaissance]].<ref name=kunitzsch/> Arcturus is also mentioned in Plato's "Laws" (844e) as a herald for the season of vintage, specifically figs and grapes.<ref>{{Cite web |title=Plato, Laws, Book 8 |url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus:text:1999.01.0166:book=8 |access-date=2025-03-03 |website=Perseus Digital Library}}</ref>

[[File:CometDonati.jpg|thumb|Arcturus next to the head of [[Comet Donati]] in 1858]]
In [[Arabic]], Arcturus is one of two stars called ''al-simāk'' "the uplifted ones" (the other is [[Spica]]). Arcturus is specified as السماك الرامح ''as-simāk ar-rāmiħ'' "the uplifted one of the lancer". The term ''Al Simak Al Ramih'' has appeared in Al Achsasi Al Mouakket catalogue (translated into [[Latin]] as ''Al Simak Lanceator'').<ref name=knobel1895/> This has been variously [[Romanization|romanized]] in the past, leading to obsolete variants such as ''Aramec'' and ''Azimech''. For example, the name ''Alramih'' is used in [[Geoffrey Chaucer]]'s ''[[A Treatise on the Astrolabe]]'' (1391). Another Arabic name is ''Haris-el-sema'', from ''حارس السماء'' ''ħāris al-samā’'' "the keeper of heaven".<ref name=arabicstar/><ref name=allen/><ref name=arabicdict/> or ''حارس الشمال'' ''ħāris al-shamāl’'' "the keeper of north".<ref name=davis1944/>

In [[Indian astronomy]], Arcturus is called Swati or [[Svati]] (Devanagari स्वाति, Transliteration IAST svāti, svātī́), possibly 'su' + 'ati' ("great goer", in reference to its remoteness) meaning very beneficent. It has been referred to as "the real pearl" in [[Bhartṛhari]]'s kāvyas.<ref>{{cite book |last=Olcott |first=William Tyler |date=2004 |title=Star Lore: Myths, Legends, and Facts |url=https://books.google.com/books?id=TIatz2DGXQwC |location=Mineola, New York |publisher=Dover Publications Inc. |pages=77–78|isbn=978-0-8021-4877-3}}</ref> 

In [[Chinese astronomy]], Arcturus is called ''Da Jiao'' ({{zh|c=大角|p=Dàjiǎo|l=great horn}}), because it is the brightest star in the [[Chinese constellation]] called ''[[Horn (Chinese constellation)|Jiao Xiu]]'' ({{zh|c=角宿|p=Jiǎo Xiǔ|l=horn star|links=no}}). Later it became a part of another constellation ''[[Neck (Chinese constellation)|Kang Xiu]]'' ({{zh|c=亢宿|p=Kàng Xiǔ|links=no}}).

The [[Wotjobaluk people|Wotjobaluk]] [[Koori]] people of southeastern Australia knew Arcturus as ''Marpean-kurrk'', mother of ''Djuit'' ([[Antares]]) and another star in Boötes, ''Weet-kurrk''<ref name=mud/> (Muphrid).<ref name=hamacher10/> Its appearance in the north signified the arrival of the larvae of the [[wood ant]] (a food item) in spring. The beginning of summer was marked by the star's setting with the Sun in the west and the disappearance of the larvae.<ref name=mud/> The people of [[Milingimbi Island]] in [[Arnhem Land]] saw Arcturus and Muphrid as man and woman, and took the appearance of Arcturus at sunrise as a sign to go and harvest ''rakia'' or [[spikerush]].<ref name=noctuary/> The [[Weilwan]] of northern New South Wales knew Arcturus as ''Guembila'' "red".<ref name="noctuary"/>{{rp|84}}

Prehistoric [[Polynesian navigation|Polynesian navigators]] knew Arcturus as ''Hōkūleʻa'', the "Star of Joy". Arcturus is the [[zenith]] star of the [[Hawaiian Islands]]. Using Hōkūleʻa and other stars, the Polynesians launched their double-hulled canoes from [[Tahiti]] and the [[Marquesas Islands]]. Traveling east and north they eventually crossed the [[equator]] and reached the [[latitude]] at which Arcturus would appear directly overhead in the summer night sky. Knowing they had arrived at the exact latitude of the island chain, they sailed due west on the [[trade winds]] to landfall. If Hōkūleʻa could be kept directly overhead, they landed on the southeastern shores of the [[Hawaii (island)|Big Island]] of Hawaii. For a return trip to Tahiti the navigators could use Sirius, the zenith star of that island. Since 1976, the [[Polynesian Voyaging Society]]'s ''[[Hōkūleʻa]]'' has crossed the Pacific Ocean many times under navigators who have incorporated this [[wayfinding]] technique in their non-instrument navigation. The crew's successful landing in [[Waitangi, Northland|Waitangi]], New Zealand on December 1985 earned them [[iwi]]hood under the name of {{lang|mi|Ngāti Ruawāhia}} (“Tribe of the Arcturus” in Māori).<ref>{{cite web |title=Moananuiākea: Aotearoa |url=https://kaiwakiloumoku.ksbe.edu/aotearoa-ngati-ruawahia |website=Kaʻiwakīloumoku Hawaiian Cultural Center |publisher=[[Kamehameha Schools]] |access-date=21 June 2025 }}<br/>– {{cite web |title=Ngāti Ruawāhia, The Sixth Tribe of Tai Tokerau Convenes at Aurere |date=Feb 10, 2018|url=https://kaiwakiloumoku.ksbe.edu/assets/img/content/moananuiakea/Ngati-Ruawahia-History.pdf}}</ref>

Arcturus had several other names that described its significance to indigenous [[Polynesia]]ns. In the [[Society Islands]], Arcturus, called ''Ana-tahua-taata-metua-te-tupu-mavae'' ("a pillar to stand by"), was one of the ten "pillars of the sky", bright stars that represented the ten heavens of the [[Tahiti]]an afterlife.<!--{{sfn|Makemson|1941|p=199}}--><ref name="makemson"/> In [[Hawaii]], the pattern of Boötes was called ''Hoku-iwa'', meaning "stars of the frigatebird". This constellation marked the path for [[Hawaiʻiloa]] on his return to Hawaii from the South Pacific Ocean.{{sfn|Makemson|1941|p=209}} The Hawaiians called Arcturus ''Hoku-leʻa''.{{sfn|Makemson|1941|p=280}} It was equated to the [[Tuamotus|Tuamotuan]] constellation ''Te Kiva'', meaning "[[frigatebird]]", which could either represent the figure of Boötes or just Arcturus.{{sfn|Makemson|1941|p=221}} However, Arcturus may instead be the Tuamotuan star called ''Turu''.{{sfn|Makemson|1941|p=264}} The Hawaiian name for Arcturus as a single star was likely ''Hoku-leʻa'', which means "star of gladness", or "clear star".{{sfn|Makemson|1941|p=210}} In the [[Marquesas Islands]], Arcturus was probably called ''Tau-tou'' and was the star that ruled the month approximating January. The [[Māori people|Māori]] and [[Moriori]] called it ''Tautoru'', a variant of the Marquesan name and a name shared with [[Orion's Belt]].{{sfn|Makemson|1941|p=260}}

In [[Inuit astronomy]], Arcturus is called the Old Man (''Uttuqalualuk'' in [[Inuit languages]]) and The First Ones (''Sivulliik'' in Inuit languages).<ref name=guide/>

The [[Miꞌkmaq]] of eastern Canada saw Arcturus as ''Kookoogwéss'', the owl.<ref name=hagar1900/>

Early-20th-century Armenian scientist [[Nazaret Daghavarian]] theorized that the star commonly referred to in [[Armenian folklore]] as ''Gutani astgh'' ([[Armenian language|Armenian]]: Գութանի աստղ; lit. star of the plow) was in fact Arcturus, as the [[constellation]] of [[Boötes]] was called "Ezogh" ([[Armenian language|Armenian]]: Եզող; lit. the person who is plowing) by Armenians.<ref name=daghavarian/>

==In popular culture==
In [[Ancient Rome]], the star's celestial activity was supposed to portend tempestuous weather, and a personification of the star acts as narrator of the prologue to [[Plautus]]'s comedy ''[[Rudens]]'' (circa 211 BC).<ref name=plautus/><ref name=Lewis_Short_1879/>

The ''[[Kāraṇḍavyūha Sūtra]]'', compiled at the end of the 4th century or beginning of the 5th century, names one of [[Avalokiteśvara]]s [[Samadhi|meditative absorptions]] as "The face of Arcturus".<ref name=roberts2013/>

One of the possible etymologies offered for the name "[[Arthur]]" assumes that it is derived from "Arcturus" and that the late 5th to early 6th-century figure on whom the myth of [[King Arthur]] is based was originally named for the star.<ref name=Lewis_Short_1879/><ref>{{cite book | last=Zimmer | first=Stefan | title=Die keltischen Wurzeln der Artussage: mit einer vollständigen Übersetzung der ältesten Artuserzählung Culhwch und Olwen | language=German | date=February 1, 2006 | page=37 | isbn=978-3825351076 | publisher=Universitätsverlag }}</ref><ref>{{cite journal | last=Zimmer | first=Stefan | title=The Name of Arthur – A New Etymology | journal=Journal of Celtic Linguistics | volume=13 | issue=1 | date=March 2009 | publisher=University of Wales Press | pages=131–136 }}</ref><ref>{{cite book | last1=Walter | first1=Philippe | translator-last=Faccia | translator-first=M. | language=Italian | title=Artù. L'orso e il re | publisher=Edizioni Arkeios | date=2005 | page=74 | isbn=978-8886495806 }}</ref><ref>{{cite book | last=Johnson | first=Flint | title=The British sources of the abduction and Grail romances | publisher=University Press of America | date=2002 | pages=38–39 | isbn=978-0761822189 | url=https://books.google.com/books?id=V70nCDxlFgEC&pg=PA38 }}</ref><ref>{{cite book | last=Chambers | first=Edmund Kerchever | title=Arthur of Britain | publisher=Speculum Historiale | date=1964 | page=170 }}</ref>

In the [[Middle Ages]], Arcturus was considered a [[Behenian fixed star]] and attributed to the stone [[jasper]] and the [[Plantago|plantain]] herb. [[Cornelius Agrippa]] listed its [[Kabbalah|kabbalistic]] sign [[Image:Agrippa1531 Alchameth.png]] under the alternate name ''Alchameth''.<ref name=tyson1993/>

Arcturus's light was employed in the mechanism used to open the [[Century of Progress|1933 Chicago World's Fair]]. The star was chosen as it was thought that light from Arcturus had started its journey at about the time of the [[World's Columbian Exposition|previous Chicago World's Fair]] in 1893 (at 36.7&nbsp;light-years away, the light actually started in 1896).<ref name=century/>

At the height of the American Civil War, President Abraham Lincoln observed Arcturus through a 9.6-inch refractor telescope when he visited the Naval Observatory in Washington, D.C., in August 1863.<ref>{{cite web | first=Rich | last=Talcott | date=July 14, 2014 | title=Lincoln and the cosmos | website=Astronomy Magazine | url=https://cs.astronomy.com/asy/b/astronomy/archive/2014/07/14/lincoln-and-the-cosmos.aspx | access-date=2022-08-28  }}</ref>

Scottish author [[David Lindsay (novelist)|David Lindsay]]'s 1920 science-fiction novel ''A Voyage to Arcturus'' takes place on the fictional planet Tormance, orbiting the star of Arcturus. In the novel Arcturus is portrayed as a [[double star]], consisting of the two fictional stars Branchspell and Alppain.<ref>{{Cite web |last=Lindsay |first=David |title=A Voyage to Arcturus |url=https://www.gutenberg.org/cache/epub/1329/pg1329-images.html |access-date=2025-09-15 |website=Project Gutenberg |language=en}}</ref> The novel later influenced [[C. S. Lewis|C.S. Lewis]]' [[The Space Trilogy|''Space Trilogy'']] (1938-1945).<ref>{{Cite web |last=Law |first=Casey R. |date=1998-09-01 |title=A Voyage to Arcturus, C. S. Lewis, and The Dark Tower |url=https://www.discovery.org/a/882/ |access-date=2025-09-15 |website=Discovery Institute |language=en-US}}</ref>

In the 2016 film ''[[Passengers (2016 film)|Passengers]]'', the starship ''Avalon'' along with the main characters perform a [[slingshot maneuver]] around Arcturus on their journey to a distant solar system.<ref>{{Cite web|url=https://www.geekwire.com/2016/jon-spaihts-physics-interstellar-travel-passengers-movie/|title=How screenwriter Jon Spaihts worked the physics of starship travel into ‘Passengers’|first=Alan|last=Boyle|date=December 21, 2016}}</ref>

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<ref name=schaaf>{{cite book| first=Fred | last=Schaaf | date=2008 | title=The Brightest Stars: Discovering the Universe Through the Sky's Most Brilliant Stars | pages=126–36 | publisher=[[John Wiley and Sons]]|location=Hoboken, New Jersey | isbn=978-0-471-70410-2 | bibcode=2008bsdu.book.....S }}</ref>

<ref name=rao2007>{{cite news |last1=Rao |first1=Joe |title=Arc to Arcturus, Speed on to Spica |url=https://www.space.com/3953-arc-arcturus-speed-spica.html |access-date=14 August 2018 |work=Space.com |date=June 15, 2007}}</ref>

<ref name=earthsky>{{cite news |title=Follow the arc to Arcturus, and drive a spike to Spica {{!}} EarthSky.org |url=https://earthsky.org/tonight/follow-the-arc-to-arcturus |access-date=14 August 2018 |work=earthsky.org |date=April 8, 2018}}</ref>

<ref name=rogers982>{{cite journal | last = Rogers | first = John H. | date = 1998 | title = Origins of the Ancient Constellations: II. The Mediterranean Traditions | journal = [[Journal of the British Astronomical Association]] | publisher=[[British Astronomical Association]]|location=London, England| volume = 108 | issue = 2 | pages = 79–89 | bibcode = 1998JBAA..108...79R}}</ref>

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<ref name=abia>{{cite journal|bibcode=2012A&A...548A..55A|arxiv=1210.1160|title=Carbon and oxygen isotopic ratios in Arcturus and Aldebaran. Constraining the parameters for non-convective mixing on the red giant branch|journal=Astronomy & Astrophysics|volume=548|pages=A55|last1=Abia|first1=C.|last2=Palmerini|first2=S.|last3=Busso|first3=M.|last4=Cristallo|first4=S.|date=2012|doi=10.1051/0004-6361/201220148|s2cid=56386673}}</ref>

<ref name=Sennhauser2011>{{cite journal | title=First detection of a weak magnetic field on the giant Arcturus: remnants of a solar dynamo? | last1=Sennhauser | first1=C. | last2=Berdyugina | first2=S. V. | journal=Astronomy & Astrophysics | volume=529 | id=A100 | pages=6 | date=May 2011 | doi=10.1051/0004-6361/201015445 | bibcode=2011A&A...529A.100S | doi-access=free }}</ref>

<ref name=Pavlenko2008>{{cite journal | title=The carbon abundance and <sup>12</sup>C/<sup>13</sup>C isotopic ratio in the atmosphere of Arcturus from 2.3 µm CO bands | last1=Pavlenko | first1=Ya. V. | journal=Astronomy Reports | volume=52 | issue=9 | pages=749–759 | date=September 2008 | doi=10.1134/S1063772908090060 | bibcode=2008ARep...52..749P | arxiv=0807.3667 | s2cid=119268407 }}</ref>

<ref name=perkins>{{cite journal
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<ref name=griffin1968>{{cite book | last1=Griffin | first1=R. E. |last2=Griffin | first2=R. | title=A photometric atlas of the spectrum of Arcturus, λλ3600-8825Å | publisher=Cambridge Philosophical Society |location=Cambridge | date=1968 | bibcode=1968pmas.book.....G }}</ref>

<ref name=hinckle2005>{{cite journal |bibcode=2005ASPC..336..321H |title=The Spectrum of Arcturus from the Infrared through the Ultraviolet |last1=Hinkle |first1=K. |last2=Wallace |first2=L. |journal=Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis |year=2005 |volume=336 |page=321 }}</ref>

<ref name=tsuji2009>{{cite journal |bibcode=2009A&A...504..543T |title=The K giant star Arcturus: The hybrid nature of its infrared spectrum |last1=Tsuji |first1=T. |journal=Astronomy and Astrophysics |year=2009 |volume=504 |issue=2 |page=543 |doi=10.1051/0004-6361/200912323 |arxiv=0907.0065 |s2cid=6408779 }}</ref>

<ref name=belmonte1990>{{cite journal|author=Belmonte, J. A.|author2=Jones, A. R.|author3=Palle, P. L.|author4=Roca Cortes, T.|date=1990|title=Acoustic oscillations in the K2 III star Arcturus|journal=Astrophysics and Space Science|volume=169|issue=1–2|pages=77–84|issn=0004-640X|doi=10.1007/BF00640689 |bibcode=1990Ap&SS.169...77B|s2cid=120697563}}</ref>

<ref name=kallinger>{{cite journal|bibcode=2010A&A...509A..77K|title=Oscillating red giants in the CoRoT exofield: Asteroseismic mass and radius determination|journal=Astronomy and Astrophysics|volume=509|pages=A77|last1=Kallinger|first1=T.|last2=Weiss|first2=W. W.|last3=Barban|first3=C.|last4=Baudin|first4=F.|last5=Cameron|first5=C.|last6=Carrier|first6=F.|last7=De Ridder|first7=J.|last8=Goupil|first8=M.-J.|last9=Gruberbauer|first9=M.|last10=Hatzes|first10=A.|last11=Hekker|first11=S.|last12=Samadi|first12=R.|last13=Deleuil|first13=M.|date=2010|doi=10.1051/0004-6361/200811437|arxiv=0811.4674|s2cid=15061735}}</ref>

<ref name=verhoelst2005>{{Cite journal| first1=T.|last1=Verhoelst|first2=P. J.|display-authors= 4|last2= Bordé|first3=G.|last3=Perrin|first4=L.|last4=Decin|title=Is Arcturus a well-understood K giant?|journal=Astronomy & Astrophysics|date=2005|volume=435|pages=289–301|doi=10.1051/0004-6361:20042356|last5= Eriksson|first5=K.|last6=Ridgway|first6=S. T.|last7=Schuller|first7=P. A.|last8=Traub|first8=W. A.|last9=Millan-Gabet|first9=R.|last10=Lacasse|first10=M. G.|last11=Waelkens|first11=C.|issue=1 |bibcode=2005A&A...435..289V|arxiv=astro-ph/0501669|s2cid=14176311}}, and see references therein.</ref>

<ref name=Kgiants>{{cite journal | doi=10.1086/173002|title=Long-period radial velocity variations in three K giants | last1=Hatzes | first1=A. | last2=Cochran | first2=W. | journal=[[The Astrophysical Journal]] | volume=413 | issue=1 | pages=339–348 | date=August 1993 | bibcode=1993ApJ...413..339H | doi-access=free }}</ref>

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<ref name=ridpath>{{cite web | url=http://www.ianridpath.com/startales/bootes.html#arcturus | last=Ridpath | first=Ian | title=Star Tales Boötes | access-date=27 November 2022 }}</ref>

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<ref name=allen>{{cite book | last=Allen | first=Richard Hinckley | title=Star-names and Their Meanings | date=2015 | pages=100–101 }}</ref>

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<ref name=davis1944>{{cite journal | last=Davis Jr. | first=G. A. | bibcode=1944PA.....52....8D | title=The Pronunciations, Derivations, and Meanings of a Selected List of Star Names | journal=Popular Astronomy | volume=52 | date=October 3, 1944 | page=13 }}</ref>

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<ref name=guide>{{cite web|title=Arcturus|url=https://www.constellation-guide.com/arcturus/|website=Constellation Guide|access-date=20 June 2017}}</ref>

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<ref name=daghavarian>{{cite book |last=Daghavarian |first=Nazaret |title=Ancient Armenian Religions (in Armenian) |date=1903 |page=19 |url=http://greenstone.flib.sci.am/gsdl/collect/hajgirqn/book/hayoc_hin.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://greenstone.flib.sci.am/gsdl/collect/hajgirqn/book/hayoc_hin.pdf |archive-date=2022-10-09 |url-status=live |access-date=12 February 2021}}</ref>

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<ref name=century>{{cite web | title=The opening ceremony of A Century of Progress. | work=Century of Progress World's Fair, 1933-1934 | publisher=University of Illinois-Chicago | date=January 2008 | url=https://collections.carli.illinois.edu/digital/collection/uic_cop/id/45| access-date=2022-08-28}}</ref>

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 | arxiv=1505.01529 | bibcode=2015A&A...580A.141L | s2cid=53652388 }}</ref>

}}

==Further reading==
{{Div col|small=yes}}
*{{citation | postscript=.
 | title=The Wind Temperature and Mass-loss Rate of Arcturus (K1.5 III)
 | display-authors=1 | last1=Harper | first1=Graham M.
 | last2=Ayres | first2=Thomas R. | last3=O'Gorman | first3=Eamon
 | journal=The Astrophysical Journal
 | volume=932 | issue=1 | id=57 | date=June 2022
 | page=57
 | doi=10.3847/1538-4357/ac69d6 | bibcode=2022ApJ...932...57H | s2cid=249880096
 | doi-access=free }}
*{{citation | postscript=.
 | title=Theoretical lifetimes and Stark broadening parameters for visible-infrared spectral lines of V I in Arcturus
 | last1=Isidoro-García | first1=L. | last2=de Andrés-García | first2=I.
 | last3=Moreno-Conde | first3=D. | last4=Colón | first4=C.
 | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=509 | issue=3 | pages=4538–4554 | date=January 2022
 | doi=10.1093/mnras/stab3301 | doi-access=free
 | bibcode=2022MNRAS.509.4538I }}
*{{citation | postscript=.
 | title=Disentangling the Arcturus stream
 | last1=Kushniruk | first1=Iryna | last2=Bensby | first2=Thomas
 | journal=Astronomy & Astrophysics
 | volume=631 | id=A47 | date=November 2019
 | pages=A47
 | doi=10.1051/0004-6361/201935234 | arxiv=1909.04949
 | bibcode=2019A&A...631A..47K | s2cid=202558933
 }}
*{{citation | postscript=.
 | title=Vanadium Transitions in the Spectrum of Arcturus
 | last1=Wood | first1=M. P. | last2=Sneden | first2=C.
 | last3=Lawler | first3=J. E. | last4=Den Hartog | first4=E. A.
 | last5=Cowan | first5=J. J. | last6=Nave | first6=G.
 | display-authors=1 | journal=The Astrophysical Journal Supplement Series
 | volume=234 | issue=2 | id=25 | date=February 2018
 | page=25
 | doi=10.3847/1538-4365/aa9a41 | arxiv=1712.06942
 | bibcode=2018ApJS..234...25W | s2cid=119356096
 | doi-access=free
 }}
*{{citation | postscript=.
 | title=Differential rotation and meridional flow of Arcturus
 | last1=Küker | first1=M. | last2=Rüdiger | first2=G.
 | journal=Astronomische Nachrichten
 | volume=332 | issue=1 | page=83 | date=January 2011
 | doi=10.1002/asna.201011483 | arxiv=1012.3321
 | bibcode=2011AN....332...83K }}
*{{citation | postscript=.
 | title=The limb-darkened Arcturus: imaging with the IOTA/IONIC interferometer
 | last1=Lacour | first1=S. | last2=Meimon | first2=S.
 | last3=Thiébaut | first3=E. | last4=Perrin | first4=G.
 | last5=Verhoelst | first5=T. | last6=Pedretti | first6=E.
 | last7=Schuller | first7=P. A. | last8=Mugnier | first8=L.
 | last9=Monnier | first9=J. | last10=Berger | first10=J. P.
 | last11=Haubois | first11=X. | last12=Poncelet | first12=A.
 | last13=Le Besnerais | first13=G. | last14=Eriksson | first14=K.
 | last15=Millan-Gabet | first15=R. | last16=Ragland | first16=S.
 | last17=Lacasse | first17=M. | last18=Traub | first18=W.
 | display-authors=1 | journal=Astronomy and Astrophysics
 | volume=485 | issue=2 | pages=561–570 | date=July 2008
 | doi=10.1051/0004-6361:200809611 | arxiv=0804.0192
 | bibcode=2008A&A...485..561L | s2cid=18853087
 }}
*{{citation | postscript=.
 | title=Long-Term Spectroscopic Monitoring of Arcturus
 | display-authors=1 | last1=Brown | first1=Kevin I. T.
 | last2=Gray | first2=David F. | last3=Baliunas | first3=Sallie L.
 | journal=The Astrophysical Journal
 | volume=679 | issue=2 | pages=1531–1540 | date=June 2008
 | doi=10.1086/587783 | bibcode=2008ApJ...679.1531B | s2cid=121170557
 | doi-access=free }}
*{{citation | postscript=.
 | title=Asteroseismology of red giants: photometric observations of Arcturus by SMEI
 | display-authors=1 | last1=Tarrant | first1=N. J.
 | last2=Chaplin | first2=W. J. | last3=Elsworth | first3=Y.
 | last4=Spreckley | first4=S. A. | last5=Stevens | first5=I. R.
 | journal=Monthly Notices of the Royal Astronomical Society: Letters
 | volume=382 | issue=1 | pages=L48–L52
 | date=November 2007 | doi=10.1111/j.1745-3933.2007.00387.x 
 | doi-access=free
 | arxiv=0706.3346 | bibcode=2007MNRAS.382L..48T | s2cid=5666311
 }}
*{{citation | postscript=.
 | title=Long-Term Spectroscopic and Precise Radial Velocity Monitoring of Arcturus
 | last=Brown | first=Kevin I. T.
 | journal=The Publications of the Astronomical Society of the Pacific
 | volume=119 | issue=852 | pages=237 | date=February 2007
 | doi=10.1086/512731 | bibcode=2007PASP..119..237B | s2cid=121637958
 | doi-access=free}}
*{{citation | postscript=.
 | title=The Rotation of Arcturus and Active Longitudes on Giant Stars
 | last1=Gray | first1=David F. | last2=Brown | first2=Kevin I. T.
 | journal=The Publications of the Astronomical Society of the Pacific
 | volume=118 | issue=846 | pages=1112–1118 | date=August 2006
 | doi=10.1086/507077 | bibcode=2006PASP..118.1112G | s2cid=120918694
 | doi-access=free }}
*{{citation | postscript=.
 | title=Far-Infrared and Millimeter Continuum Studies of K Giants: α Bootis and α Tauri
 | last1=Cohen | first1=Martin | last2=Carbon | first2=Duane F.
 | last3=Welch | first3=William J. | last4=Lim | first4=Tanya
 | last5=Schulz | first5=Bernhard | last6=McMurry | first6=A. D.
 | last7=Forster | first7=James R. | last8=Goorvitch | first8=David
 | display-authors=1 | journal=The Astronomical Journal
 | volume=129 | issue=6 | pages=2836–2848
 | date=June 2005 | doi=10.1086/429887 
 | arxiv=astro-ph/0502516 | bibcode=2005AJ....129.2836C | s2cid=119419198
 }}
*{{citation | postscript=.
 | title=The Extragalactic Origin of the Arcturus Group
 | display-authors=1 | last1=Navarro | first1=Julio F.
 | last2=Helmi | first2=Amina | last3=Freeman | first3=Kenneth C.
 | journal=The Astrophysical Journal
 | volume=601 | issue=1 | pages=L43–L46
 | date=January 2004 | doi=10.1086/381751 
 | arxiv=astro-ph/0311107 | bibcode=2004ApJ...601L..43N | s2cid=10638792
 }}
*{{citation | postscript=.
 | title=Oscillations in Arcturus from WIRE Photometry
 | last1=Retter | first1=Alon | last2=Bedding | first2=Timothy R.
 | last3=Buzasi | first3=Derek L. | last4=Kjeldsen | first4=Hans
 | last5=Kiss | first5=László L. | display-authors=1
 | journal=The Astrophysical Journal
 | volume=591 | issue=2 | pages=L151–L154
 | date=July 2003 | doi=10.1086/377211 
 | arxiv=astro-ph/0306056 | bibcode=2003ApJ...591L.151R | s2cid=119083930
 }}
*{{citation | postscript=.
 | title=Detection of Water Vapor in the Photosphere of Arcturus
 | last1=Ryde | first1=N. | last2=Lambert | first2=D. L.
 | last3=Richter | first3=M. J. | last4=Lacy | first4=J. H.
 | display-authors=1 | journal=The Astrophysical Journal
 | volume=580 | issue=1 | pages=447–458
 | date=November 2002 | doi=10.1086/343040 
 | arxiv=astro-ph/0207368 | bibcode=2002ApJ...580..447R | s2cid=7672420
 }}
*{{citation | postscript=.
 | title=The Effective Temperature of Arcturus
 | last1=Griffin | first1=R. E. M. | last2=Lynas-Gray | first2=A. E.
 | journal=The Astronomical Journal
 | volume=117 | issue=6 | pages=2998–3006 | date=June 1999
 | doi=10.1086/300878 | bibcode=1999AJ....117.2998G | s2cid=120907426
 | doi-access=free }}
*{{citation | postscript=.
 | title=Adaptive Optics Observations of Arcturus using the Mount Wilson 100 Inch Telescope
 | display-authors=1 | last1=Turner | first1=Nils H.
 | last2=ten Brummelaar | first2=Theo A. | last3=Mason | first3=Brian D.
 | journal=The Publications of the Astronomical Society of the Pacific
 | volume=111 | issue=759 | pages=556–558 | date=May 1999
 | doi=10.1086/316353 | bibcode=1999PASP..111..556T | s2cid=2441153
 | doi-access=free }}
*{{citation | postscript=.
 | title=Arcturus as a double star
 | last=Griffin | first=R. F.
 | journal=The Observatory
 | volume=118 | pages=299–301 | date=October 1998
 | bibcode=1998Obs...118..299G }}
*{{citation | postscript=.
 | title=Angular diameter and limb darkening of Arcturus.
 | last1=Quirrenbach | first1=A. | last2=Mozurkewich | first2=D.
 | last3=Buscher | first3=D. F. | last4=Hummel | first4=C. A.
 | last5=Armstrong | first5=J. T. | display-authors=1
 | journal=Astronomy and Astrophysics
 | volume=312 | pages=160–166 | date=August 1996
 | bibcode=1996A&A...312..160Q }}
{{Div col end}}

==External links==
{{Commons category|Arcturus}}
* [http://www.solstation.com/stars2/arcturus.htm SolStation.com entry]

{{Sky|14|15|39.7||19|10|56|37}}

{{Stars of Boötes}}
{{Portal bar|Astronomy|Stars|Outer space}}
{{Authority control}}
{{DEFAULTSORT:Arcturus}}
<!-- Properties -->
[[Category:K-type giants]]
[[Category:Suspected variables]]
[[Category:Hypothetical planetary systems]]
[[Category:Arcturus moving group]]
<!-- Other -->
[[Category:Boötes]]
[[Category:Bayer objects|Bootis, Alpha]]
[[Category:Durchmusterung objects|BD+19 2777]]
[[Category:Flamsteed objects|Bootis, 16]]
[[Category:Gliese and GJ objects|0541]]
[[Category:Henry Draper Catalogue objects|124897]]
[[Category:Hipparcos objects|069673]]
[[Category:Bright Star Catalogue objects|5340]]
[[Category:TIC objects]]
[[Category:Stars with proper names|Arcturus]]
[[Category:Lucidae]]