Arcturus

The traditional name Arcturus is Latinised from the ancient Greek Ἀρκτοῦρος (Arktouros) and means "Guardian of the Bear",{{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}} ultimately from ἄρκτος (arktos), "bear"{{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}} and οὖρος (ouros), "watcher, guardian".{{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}} As ἄρκτος also came to mean "north", the name can also translate to "Guardian of the North".{{cite web |title=IAU Catalog of Star Names |url=https://exopla.net/star-names/modern-iau-star-names/ |access-date=25 May 2025}}

The designation of Arcturus as α Boötis (Latinised to Alpha Boötis) was made by Johann Bayer in 1603. In 2016, the International Astronomical Union organized a 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.

Arcturus and its distinctive red color have been mentioned since antiquity and medieval times; Ptolemy described it as subrufa ("slightly red"), and Geoffrey Chaucer referred to it as Alramih in A Treatise on the Astrolabe (1391).

In 1635, the French mathematician and astronomer 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 supernovae.

File:BootesCC.jpg.]]

With an apparent visual magnitude of −0.05, Arcturus is the brightest star in the northern celestial hemisphere and the fourth-brightest star in the night sky, after Sirius (−1.46 apparent magnitude), 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 A (officially named Rigil Kentaurus), whose apparent magnitude {{nobr|is −0.01}}. Arcturus has been seen at or just before sunset with the naked eye.

Arcturus is visible from both of Earth's hemispheres as it is located 19° north of the celestial equator. The star 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.Schaaf, p. 257. 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 UK). By continuing in this path, one can find Spica, "Arc to Arcturus, then spike (or speed on) to Spica". Together with the bright stars Spica and Regulus (or Denebola, depending on the source), Arcturus is part of the Spring Triangle 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 (B-V +1.00) and Aldebaran (B-V +1.54).

η Boötis, or Muphrid, is only 3.3 light-years 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.

File:Arcturus (optical).png

Based upon an annual parallax shift of 88.83 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}}. Because of its proximity, Arcturus has a high proper motion, two arcseconds a year, greater than any first magnitude star other than α Centauri. It is the second-closest giant star to Earth, after 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.) Arcturus is thought to be an old-disk star, and appears to be moving with a group of 52 other such stars, known as the Arcturus stream.

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) power output is about 180 times that of the Sun. With a near-infrared J band 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 efficacy as the star has a lower 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.

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}}, while the oxygen isotope ratio for a first dredge-up star gives a mass of {{solar mass|1.2}}. The star, given its evolutionary state, is expected to have undergone significant mass loss in the past. The star displays magnetic activity that is heating the coronal structures, and it undergoes a 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. The magnetic activity appears to lie along four latitudes and is rotationally modulated.

Arcturus is estimated to be around 6 to 8.5 billion years old, but there is some uncertainty about its evolutionary status. Based upon the 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 core to ignite the helium flash. It has likely exhausted the hydrogen from its core and is now in its active 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.

File:Sun to Arcturus comparison.jpg, Beta Ursae Majoris, Pollux, and Arcturus.]]

Arcturus has evolved off the main sequence to the red giant branch, reaching an early K-type stellar classification. It is frequently assigned the spectral type of K0III, but in 1989 was used as the spectral standard for type K1.5III Fe−0.5, with the suffix notation indicating a mild underabundance of iron compared to typical stars of its type. As the brightest K-type giant in the sky, it has been the subject of multiple atlases with coverage from the ultraviolet to infrared.

The spectrum shows a dramatic transition from emission lines in the ultraviolet to atomic absorption lines in the visible range and molecular absorption lines in the infrared. This is due to the optical depth of the atmosphere varying with wavelength. The spectrum shows very strong absorption in some molecular lines that are not produced in the photosphere but in a surrounding shell. 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 chromospheric wind steeply accelerating to 35–40 km/s in this region.

Astronomers term "metals" those elements with higher atomic numbers 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.

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 μHz (2.7 days) with an amplitude of 60 ms⁻¹, with a frequency separation of c. 5 μHz. They suggested that the most plausible explanation for the variability of Arcturus is stellar oscillations.

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.

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.

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 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 astronomical units. 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.

File:Hugo-de-Groot-Syntagma-Arateorum MG 0605.tif

{{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 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 Hyginus's Astronomy.

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.

An alternative lore associates the name with the legend around 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, Maira, became Canicula (Procyon), although "Arcturus" here may be used in the sense of the constellation rather than the star.{{harvp|Eratosthenes|Hyginus|Aratus|Hard (tr.)|2015|pp=38–40}}, p. 182 (note to p. 40)

As one of the 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", or SHU-PA of unknown derivation in the Three Stars Each Babylonian star catalogues and later MUL.APIN around 1100 BC.

In ancient Greek, the star is found in ancient astronomical literature, e.g. Hesiod's Work and Days, circa 700 BC, 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.{{Cite book |title=Star-names and Their Meanings |publisher=Richard Hinckley Allen |orig-year=1899 |year=2015|isbn=9789333375757 |edition=1st}} It fell out of use in favour of Arabic names until it was revived in the Renaissance. Arcturus is also mentioned in Plato's "Laws" (844e) as a herald for the season of vintage, specifically figs and grapes.{{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=www.perseus.tufts.edu}}

File:CometDonati.jpg 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). This has been variously 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". or حارس الشمال ħāris al-shamāl’ "the keeper of north".

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.{{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}}

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 Jiao Xiu ({{zh|c=角宿|p=Jiǎo Xiǔ|l=horn star|links=no}}). Later it became a part of another constellation Kang Xiu ({{zh|c=亢宿|p=Kàng Xiǔ|links=no}}).

The Wotjobaluk Koori people of southeastern Australia knew Arcturus as Marpean-kurrk, mother of Djuit (Antares) and another star in Boötes, Weet-kurrk (Muphrid). 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. 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. The Weilwan of northern New South Wales knew Arcturus as Guembila "red".{{rp|84}}

Prehistoric 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 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.

Arcturus had several other names that described its significance to indigenous Polynesians. 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 Tahitian afterlife. 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 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 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).

The Miꞌkmaq of eastern Canada saw Arcturus as Kookoogwéss, the owl.

Early-20th-century Armenian scientist Nazaret Daghavarian theorized that the star commonly referred to in Armenian folklore as Gutani astgh (Armenian: Գութանի աստղ; lit. star of the plow) was in fact Arcturus, as the constellation of Boötes was called "Ezogh" (Armenian: Եզող; lit. the person who is plowing) by Armenians.

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' comedy Rudens (circa 211 BC).

The Kāraṇḍavyūha Sūtra, compiled at the end of the 4th century or beginning of the 5th century, names one of Avalokiteśvaras meditative absorptions as "The face of Arcturus".

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.{{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 }}{{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 }}{{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 }}{{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 }}{{cite book | last=Chambers | first=Edmund Kerchever | title=Arthur of Britain | publisher=Speculum Historiale | date=1964 | page=170 }}

In the Middle Ages, Arcturus was considered a Behenian fixed star and attributed to the stone jasper and the plantain herb. Cornelius Agrippa listed its kabbalistic sign Image:Agrippa1531 Alchameth.png under the alternate name Alchameth.

Arcturus's light was employed in the mechanism used to open the 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 previous Chicago World's Fair in 1893 (at 36.7 light-years away, the light actually started in 1896).

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.{{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 }}

An Anacondrai general from Ninjago (TV series) is also named Arcturus.{{cn|date=April 2025}}

In the Fallout 4 DLC Nuka-World, an in-game location which was built by Vault-Tec to demonstrate how Vaults might be used for space colonisation uses the name “Arcturus I”.{{cn|date=April 2025}}

{{Reflist|refs=

{{Cite journal| last1=Schröder | first1=K.-P. | last2=Cuntz | first2=M. | title=A critical test of empirical mass loss formulas applied to individual giants and supergiants | journal=Astronomy and Astrophysics | publisher=IOP Publishing| location=Bristol, England| volume=465 | issue=2 | pages=593–601 |date=April 2007 | doi=10.1051/0004-6361:20066633 | bibcode=2007A&A...465..593S |arxiv = astro-ph/0702172| s2cid=55901104 }}

{{Cite journal| display-authors=1 | last1=Carney | first1=Bruce W. | last2=Gray | first2=David F. | last3=Yong | first3=David | last4=Latham | first4=David W. | last5=Manset | first5=Nadine | last6=Zelman | first6=Rachel | last7=Laird | first7=John B. | title=Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars | journal=The Astronomical Journal | publisher=EDP Sciences| location=Paris, France| volume=135 | issue=3 | pages=892–906 |date=March 2008 | doi=10.1088/0004-6256/135/3/892 | bibcode=2008AJ....135..892C |arxiv = 0711.4984| s2cid=2756572 }}

{{cite book|last=Makemson |first=Maud Worcester |title= The Morning Star Rises: an account of Polynesian astronomy |publisher=Yale University Press |location=New Haven, Connecticut| date=1941 |url=https://books.google.com/books?id=i5giAAAAMAAJ&q=%22arcturus%22 |page=199|bibcode=1941msra.book.....M }}

{{Cite journal | bibcode=2011ApJ...743..135R | title=Fundamental Parameters and Chemical Composition of Arcturus | journal=The Astrophysical Journal | publisher=IOP Publishing| location=Bristol, England| volume=743 | issue=2 | pages=135 | date=December 2011 | first1=I. | last1=Ramírez| first2=C. | last2=Allende Prieto | doi=10.1088/0004-637X/743/2/135 | arxiv=1109.4425 | s2cid=119186472 }}

{{cite journal | first=Florian | last=van Leeuwen | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | location=Paris, France| volume=474 | issue=2 | pages=653–64 | date=November 2007 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | arxiv=0708.1752| s2cid=18759600 }}

{{cite journal|bibcode=2003AJ....126.2048G|title=Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I|journal=The Astronomical Journal| location=Bristol, England| volume=126|issue=4|pages=2048|last1=Gray|first1=R. O.|last2=Corbally|first2=C. J.|last3=Garrison|first3=R. F.|last4=McFadden|first4=M. T.|last5=Robinson|first5=P. E.|date=2003|doi=10.1086/378365|arxiv = astro-ph/0308182 |s2cid=119417105}}

{{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|pages=0|last1=Ducati|first1=J. R.|date=2002}}

{{cite journal|bibcode=2008AJ....135..209M|title=Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity|journal=The Astronomical Journal|volume=135|issue=1|pages=209–231|last1=Massarotti|first1=Alessandro|last2=Latham|first2=David W.|last3=Stefanik|first3=Robert P.|last4=Fogel|first4=Jeffrey|date=2008|doi=10.1088/0004-6256/135/1/209|doi-access=free}}

{{cite web|url=http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-source=I/239/tyc_main&HIP=69673|title=HIP 69673|work=The Hipparcos and Tycho Catalogues|author=Perryman|date=1997|display-authors=etal}}

{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |access-date=28 July 2016}}

{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}

{{cite book | title=The Hundred Greatest Stars | last=Kaler | first=James B. | date=2002 | publisher=Copernicus Books | location=New York City | isbn=978-0-387-95436-3 | page=21}}

{{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 }}

{{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}}

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

{{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}}

{{cite journal|bibcode=2012MNRAS.425.3188R|arxiv=1207.0767|title=Chemical compositions of stars in two stellar streams from the Galactic thick disc|journal=Monthly Notices of the Royal Astronomical Society|volume=425|issue=4|pages=3188|last1=Ramya|first1=P.|last2=Reddy|first2=Bacham E.|last3=Lambert|first3=David L.|date=2012|doi=10.1111/j.1365-2966.2012.21677.x|doi-access=free |s2cid=119253279}}

{{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}}

{{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 }}

{{cite journal | title=The carbon abundance and ¹²C/¹³C 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 }}

{{cite journal

| last1=Keenan | first1=Philip C. | last2=McNeil | first2=Raymond C.

| title=The Perkins catalog of revised MK types for the cooler stars

| journal=The Astrophysical Journal Supplement Series

| volume=71 | pages=245 | year=1989

| doi=10.1086/191373 | bibcode=1989ApJS...71..245K }}

{{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 }}

{{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 }}

{{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 }}

{{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}}

{{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}}

{{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.

{{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 }}

{{cite book|ref={{SfnRef|Eratosthenes|Hyginus|Aratus|Hard (tr.)|2015}}|author1=Eratosthenes |author2=Hyginus |author3=Aratus |others=Hard, Robin (transl.) |title=Eratosthenes and Hyginus: Constellation Myths, with Aratus's Phaenomena |publisher=Oxford University Press |year=2015 |url=https://books.google.com/books?id=7IMSBwAAQBAJ&pg=PA36 |pages=5–7, 35–37|isbn=9780198716983 }}

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

{{cite journal|last=Knobel|first=E. B.|title=Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket|journal=Monthly Notices of the Royal Astronomical Society|volume=55|issue=8|page=429|date=June 1895|bibcode= 1895MNRAS..55..429K|doi=10.1093/mnras/55.8.429|doi-access=free}}

{{cite web|url=http://www.jas.org.jo/arabic/alma.html|title=List of the 25 brightest stars|website=Jordanian Astronomical Society|access-date=March 28, 2007|archive-date=March 16, 2012|archive-url=https://web.archive.org/web/20120316023454/http://www.jas.org.jo/arabic/alma.html|url-status=dead}}

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

{{cite book | last=Wehr | first=Hans | editor1-last=Cowan | editor1-first=J. Milton | title=A dictionary of modern written Arabic | date=1994 }}

{{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 }}

{{cite book | last1=Kunitzsch | first1=Paul | last2=Smart | first2=Tim | date=2006 | title=A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations | edition=2nd rev. | publisher=Sky Pub | location=Cambridge, MA | isbn=978-1-931559-44-7 | page=19 }}

{{Cite book | first1=Mudrooroo | last1=Nyoongah | first2=Mudrooroo | last2=Narogin | title=Aboriginal mythology : an A-Z spanning the history of aboriginal mythology from the earliest legends to the present day | publisher=HarperCollins | location=London | date=1994 | page=5 | isbn=978-1-85538-306-7 }}

{{cite journal | last1=Hamacher | first1=Duane W. | last2=Frew | first2=David J. | date=2010 | title=An Aboriginal Australian Record of the Great Eruption of Eta Carinae | journal=Journal of Astronomical History & Heritage | volume=13 | issue=3 | pages=220–34 | doi=10.3724/SP.J.1440-2807.2010.03.06 | arxiv=1010.4610 | bibcode=2010JAHH...13..220H | s2cid=118454721 }}

{{cite book|last=Johnson|first=Diane|title=Night skies of aboriginal Australia: a noctuary|publisher=University of Sydney|location=Darlington, New South Wales|date=1998|pages=[https://archive.org/details/nightskiesofabor0000john/page/24 24, 69, 84, 112]|isbn=978-1-86451-356-1|bibcode=1998nsaa.book.....J|url-access=registration|url=https://archive.org/details/nightskiesofabor0000john/page/24}}{{rp|24,69,112}}

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

{{cite journal|last=Hagar|first=Stansbury |date=1900|title=The Celestial Bear|journal=The Journal of American Folklore|volume=13|issue=49|pages=92–103|jstor=533799|doi=10.2307/533799}}

{{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}}

{{cite journal | last = Rogers | first = John H. | date = 1998 | title = Origins of the Ancient Constellations: I. The Mesopotamian Traditions | journal = Journal of the British Astronomical Association | volume = 108 | issue = 1 | pages = 9–28 | bibcode = 1998JBAA..108....9R}}

{{cite news|author=Plautus |author-link=Plautus |title=Rudens|page= prol. 71}}

{{cite book | chapter-url=https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0059%3Aentry%3Darcturus | chapter=arctūrus | first1=Charlton T. | last1=Lewis | first2=Charles | last2=Short | title=A Latin Dictionary | publisher=Clarendon Press | publication-place=Oxford | date=1879 }} Available on the Perseus Digital Library.

{{cite book | first1=Donald | last1=Tyson | last2=Freake | first2=James | date=1993 | title=Three Books of Occult Philosophy | publisher=Llewellyn Worldwide | isbn=978-0-87542-832-1 }}

{{Cite web|url=http://www.pacificbuddha.org/wp-content/uploads/2014/02/Karandavyuha-Sutra.pdf|title=Karandavyuha Sutra Page 45|last1=Alan Roberts|first1=Peter|last2=Yeshi|first2=Tulku|date=2013|website=Pacificbuddha|publisher=84000}}

{{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}}

{{cite journal | last1=Jijelava | first1=B.| last2=Holbrook | first2=J. | last3=Simonia | first3=I. | date=2016 | title=Astronomical context of Georgian folklore | url=https://doi.org/10.17485/ijst/2016/v9i37/94312 | journal=Indian Journal of Science and Technology | volume=9 | issue=37 | pages=1-8 | doi=10.17485/ijst/2016/v9i37/94312}}

{{citation

| editor-last = Skeat

| editor-first = Walter W

| editor-link = Walter William Skeat

| title = A treatise on the astrolabe by Geoffrey Chaucer

| year = 1872

| publisher = for The Early English Text Society by N. Trűbner & Co

| url = https://archive.org/stream/atreatiseonastr00skeagoog#page/n10

| access-date = 26 August 2018}}

{{cite journal

| title=Spatially resolving the thermally inhomogeneous outer atmosphere of the red giant Arcturus in the 2.3 μm CO lines

| last1=Ohnaka | first1=K. | last2=Morales Marín | first2=C. A. L.

| journal=Astronomy & Astrophysics

| volume=620 | id=A23 | pages=10 | date=November 2018

| doi=10.1051/0004-6361/201833745 | arxiv=1809.01181

| bibcode=2018A&A...620A..23O | s2cid=119095123 }}

{{cite journal

| title=Models of red giants in the CoRoT asteroseismology fields combining asteroseismic and spectroscopic constraints

| last1=Lagarde | first1=N. | last2=Miglio | first2=A.

| last3=Eggenberger | first3=P. | last4=Morel | first4=T.

| last5=Montalbán | first5=J. | last6=Mosser | first6=B.

| last7=Rodrigues | first7=T. S. | last8=Girardi | first8=L.

| last9=Rainer | first9=M. | last10=Poretti | first10=E.

| last11=Barban | first11=C. | last12=Hekker | first12=S.

| last13=Kallinger | first13=T. | last14=Valentini | first14=M.

| last15=Carrier | first15=F. | last16=Hareter | first16=M.

| last17=Mantegazza | first17=L. | last18=Elsworth | first18=Y.

| last19=Michel | first19=E. | last20=Baglin | first20=A.

| display-authors=1 | journal=Astronomy & Astrophysics

| volume=580 | id=A141 | date=August 2015

| pages=A141 | doi=10.1051/0004-6361/201525856

| arxiv=1505.01529 | bibcode=2015A&A...580A.141L | s2cid=53652388 }}

}}

{{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}}

{{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}}

Category:K-type giants

Category:Suspected variables

Category:Hypothetical planetary systems

Category:Arcturus moving group

Category:Boötes

Bootis, Alpha

BD+19 2777

Bootis, 16

0541

124897

069673

5340

Category:TIC objects

Arcturus