View source for Achernar

{{short description|Brightest star in the constellation Eridanus}}
{{hatnote group|
{{distinguish|Achenar|Acamar}}
{{other uses}}
}}
{{Starbox begin}}
{{Starbox image
 | image=
{{Location mark
|image=Eridanus constellation map.svg|alt=|float=center|width=240
|label=|position=right
|mark=Red circle.svg|mark_width=12|mark_link=Achernar
|x=827|y=1175
}}
|caption=Location of Achernar (circled)
}}
{{Starbox observe
| epoch = J2000
| constell = [[Eridanus (constellation)|Eridanus]]
| ra = {{RA|01|37|42.84548}}<ref name=aaa474_2_653/>
| dec = {{DEC|-57|14|12.3101}}<ref name=aaa474_2_653/>
| appmag_v = 0.40–0.46<ref name=gcvs/>
| pronounce = {{IPAc-en|'|eɪ|k|ər|n|ɑr}}<ref>{{MW|Achernar}}</ref>
}}
{{Starbox character
| class = B3&nbsp;Vpe<ref name=aaaa601_a118/> + A1V-A3V<ref name=aaa484_1_L13/>
| b-v = −0.16<ref name=ducati/>
| u-b = −0.66<ref name=ducati/>
| variable=[[Be star|Be]]<ref name=gcvs/>
}}
{{Starbox astrometry
| radial_v = +16<ref name=rgcrv/>
| prop_mo_ra = 87.00{{±|0.58}}<ref name=aaa474_2_653/>
| prop_mo_dec = −38.24{{±|0.50}}<ref name=aaa474_2_653/>
| gal_lat = −58.7920
| gal_lon = 290.8412
| parallax = 23.39
| p_error = 0.57
| parallax_footnote = <ref name=aaa474_2_653/>
| absmag_v = {{val|-2.74|0.05}}<ref name=neuhauser/>
}}
{{Starbox orbit
| reference = <ref name=kervella/>
| period = {{val|7.0389|0.0015}}
| axis = {{val|0.17190|0.00025}}
| axis_unitless = {{val|7.35|0.18|ul=AU}}
| eccentricity = {{val|0.7258|0.0015}}
| inclination = {{val|30.32|0.35}}
| node = {{val|310.91|0.80}}
| periastron = {{val|2008.7582|0.0014}}
| periarg = {{val|172.05|0.87}}
}}
{{Starbox detail
| component1 = A
| age_myr = 63<ref name=kervella/>
| metal_fe =
| mass = 6.0<ref name=kervella/>
| radius = 6.78 – 9.16<ref name=souza2014/>
| rotational_velocity = 250<ref name=aaa493_3_L53/>
| luminosity = {{val|3,493|429|fmt=commas}}<ref name=kervella/>
| gravity = 2.772 – 3.561<ref name=souza2014/>
| temperature = 12,673 – 17,124<ref name=souza2014/>
| component2 = B
| mass2 = {{val|2.0|0.1}}<ref name=kervella/>
| luminosity2 = {{val|17.5|5.1}}<ref name=kervella/>
| temperature2 = {{val|9,064|624|fmt=commas}}<ref name=kervella/>
| radius2 = {{val|1.70|0.08}}<ref name=kervella/>
}}
{{Starbox catalog
| names= {{odlist | name=Achernar | B=α Eri | Gould=2 G. Eri | CD=−57°316 | CPD=−57°334 | FK5=54 | HD=10144 | HIP=7588 | HR=472 | SAO=232481 }}<ref name="SIMBAD"/><ref name=Gould1879/>
}}
{{Starbox reference
| Simbad = Achernar
}}
{{Starbox end}}

'''Achernar''' is the brightest [[star]] in the [[constellation]] of [[Eridanus (constellation)|Eridanus]] and the [[list of brightest stars|ninth-brightest]] in the night sky. It has the [[Bayer designation]] '''Alpha Eridani''', which is [[Romanization|Latinized]] from '''α Eridani''' and abbreviated '''Alpha Eri''' or '''α Eri'''. The name Achernar applies to the primary component<ref name="IAU-LSN"/> of a [[binary star|binary system]].<ref name=aaa484_1_L13/> The two components are designated Alpha Eridani A (the primary) and B (the secondary), with the latter known informally as Achernar B. As determined by the ''[[Hipparcos]]'' [[astrometry]] satellite,<ref name=aaa323_L49/><ref name=GSM/> this system is located at a distance of approximately {{convert|139|ly|pc|abbr=off|lk=on}} from the [[Sun]].<ref name=aaa474_2_653/>

Of the ten brightest stars in the night-time sky by [[apparent magnitude]],{{#tag:ref|The ten brightest stars in the nighttime sky in terms of apparent magnitude are, from brightest to dimmest, [[Sirius]], [[Canopus]], [[Alpha Centauri]], [[Arcturus]], [[Vega]], [[Capella (star)|Capella]], [[Rigel]], [[Procyon]], Achernar, and [[Betelgeuse]]|group="nb"}} Alpha Eridani is the hottest and bluest in color because it is [[spectral type]] B. Achernar has an unusually rapid [[stellar rotation|rotational velocity]], causing it to become [[Oblate spheroid|oblate]] in shape. The secondary is smaller, is [[A-type main-sequence star|spectral type A]], and orbits Achernar at a distance of {{val|7.35|ul=AU}}.

==Nomenclature==
''α Eridani'' ([[Latinisation of names|Latinised]] to ''Alpha Eridani'') is the system's [[Bayer designation]]. The designations of the two components—''Alpha Eridani A'' and ''B''—derive from the convention used by the [[Washington Multiplicity Catalog]] (WMC) for multiple [[star system]]s, and adopted by the [[International Astronomical Union]] (IAU).<ref name="planetnaming"/>

The system bears the traditional name of ''Achernar'' (sometimes spelled ''Achenar''), derived from the [[Arabic]] {{lang|ar|آخر النهر}} ''{{Transliteration|ar|ākhir an-nahr}}'', meaning "The End of the River".{{#tag:ref|In modern Arabic {{lang|ar|آخر النهر}} means  "down the river".<ref name="reverso_context"/>|group="nb"}} However, it seems that this name originally referred to [[Theta Eridani]] instead, which latterly was known by the similar traditional name ''Acamar'', with the same etymology.<ref name=allen/> The [[IAU Working Group on Star Names]] (WGSN) approved the name with the spelling ''Achernar'' for the component ''Alpha Eridani A'' on 30&nbsp;June 2016 and it is now so included in the List of IAU-approved Star Names.<ref name="IAU-LSN"/><ref name="WGSN"/><ref name="TriRpt18"/>

In [[Chinese language|Chinese]] caused by adaptation of the European Southern Hemisphere constellations into the Chinese system, {{lang|zh|水委}} ({{lang|zh-Latn|Shuǐ Wěi}}), meaning ''[[Chinese constellations#The Southern Asterisms|Crooked Running Water]]'', refers to an [[Asterism (astronomy)|asterism]] consisting of Achernar, [[Zeta Phoenicis|ζ Phoenicis]] and [[Eta Phoenicis|η Phoenicis]]. Consequently, Achernar itself is known as {{lang|zh|水委一}} ({{lang|zh-Latn|Shuǐ Wěi yī}}, {{langx|en|the First Star of Crooked Running Water}}).<ref name=aeea/>

The indigenous [[Wergaia|Boorong]] people of northwestern [[Victoria (Australia)|Victoria]], Australia, named it ''Yerrerdetkurrk''.<ref name=hamacher/> The [[Wardaman people|Wardaman]] name is ''Gawalyan'', the [[echidna]].<ref name=IAU-CSN-new/>

===Namesake===
[[USS Achernar|USS ''Achernar'' (AKA-53)]] was a [[United States Navy]] attack cargo ship named after the star.<ref name=danfs/>

==Properties==
Achernar is in the deep southern sky and never rises above the horizon north of 33°N, roughly the latitude of [[Dallas]], Texas. It is best seen from the [[Southern Hemisphere]] in November; it is [[Circumpolar star|circumpolar]] south of 33°S, roughly the latitude of [[Santiago]]. At this latitude—e.g., the south coast of South Africa ([[Cape Town]] to [[Port Elizabeth]])—when at lower culmination it is only 1 degree above the horizon. Further south, it is visible at all times during night.

[[File:AlphaEriLightCurve.png|thumb|left|A [[light curve]] for Alpha Eridani, plotted from ''[[Transiting Exoplanet Survey Satellite|TESS]]'' data,<ref name=MAST/> with the 1.263-day period listed in the [[General Catalogue of Variable Stars|GCVS]] shown in red]]
Achernar is a bright, blue star about six to seven times the [[mass of the Sun]]. It has a [[stellar classification]] of B6&nbsp;Vep, but despite appearing similar to a [[main sequence star]], it is thought to have recently exhausted the hydrogen in its core and begun to evolve away from the main sequence.<ref name=kervella/> It has expanded to an average radius eight times [[solar radius|the Sun's]] and is about 3,000 times [[Solar luminosity|more luminous]]. Infrared observations of the star using an adaptive optics system on the [[Very Large Telescope]] show that it has a companion star in a close orbit. This appears to be an A-type star in the stellar classification range A0V–A3V, which suggests a stellar mass of about double [[solar mass|that of the Sun]]. The separation of the two stars is {{val|7.35|u=AU}} and their orbital period is 7 years.<ref name=aaa484_1_L13/>

The brightness of Achernar varies very slightly, by a maximum of 0.06 magnitudes or about 6%. A period of {{val|1.263|u=days}} is given in the [[General Catalogue of Variable Stars]],<ref name=gcvs/> but several periods have been identified between about {{val|17|u=hours}} and {{val|35|u=hours}}.  The longest periods are very similar to the rotation period of the star, although the exact period appears to vary as the rotational velocity of its upper atmosphere changes. The shortest periods may be harmonics of the longer periods.  The variability type of Achernar is given only as a Be star and the exact causes of the brightness changes are unknown.  The star itself appears to pulsate and the disk around it varies in size and shape as well as apparently disappearing at times.<ref name=balona2020/>

[[File:Achernar.svg|thumb|left|upright|Extreme rotation speed has [[Oblate spheroid|flattened]] Achernar.]]
As of 2015, Achernar was the least [[spherical]] star known in the [[Milky Way]].<ref name=kong2015/> It spins so rapidly that it has assumed the shape of an [[oblate spheroid]] with an equatorial diameter 35% greater than its polar diameter. The oblateness of Achernar is comparable to that of the dwarf planet [[Haumea]], and the stars of [[Altair]] and [[Regulus]]. The polar axis is inclined about 60.6° to the line of sight from the Earth.<ref name=souza2014/> Since it is actually a binary star, its highly distorted shape may cause non-negligible departures of the companion's orbital trajectory with respect to a [[Kepler orbit|Keplerian ellipse]].

Because of the distorted shape of this star, there is a significant temperature variation by latitude. At the pole, the temperature is {{Val|17124|fmt=commas|ul=K}}, while the equator is at {{val|12673|fmt=commas|u=K}}. The average temperature of the star is about {{val|15000|fmt=commas|u=K}}. The high polar temperatures are generating a fast polar wind that is ejecting matter from the star, creating a polar envelope of hot gas and plasma. The entire star is surrounded by an extended envelope that can be detected by its [[infrared excess|excess infrared emission]],<ref name=aaa493_3_L53/> or by its polarization.<ref name=apj671_1_L49/> The presence of a circumstellar disk of ionized gas is a common feature of [[Be star]]s such as this.<ref name=apj671_1_L49/> The disk is not stable and periodically collapses back into the star. The maximum polarization for Achernar's disk was observed in September 2014, and it is now decreasing.<ref name=cotton/>
{{clear left}}

==Co-moving companion==
The [[red dwarf]] 2MASS J01375879−5645447 lies about half a degree north of Achernar.  It has been identified as being at the same distance and sharing a [[common proper motion]], as well as being of about the same age.  The projected separation of the two is slightly over one light year and they would not be gravitationally bound, but it is proposed that both are part of the [[Tucana-Horologium association]].<ref name=kervella/>

==Historical visibility==
{{More citations needed section|date=June 2024}}
[[axial precession|Precession]] caused Achernar to lie much further south in ancient times than at present: 7.5 degrees from the south celestial pole around 3400&nbsp;BCE (declination {{DEC|−82|40}})<ref name="Stellarium"/> and still as far south as declination {{DEC|−76}} by around 1500&nbsp;BCE. Hence the [[Ancient Egypt]]ians could not have known it. Even in 100&nbsp;CE, its declination was around {{DEC|−67}}, meaning [[Ptolemy]] could not possibly have seen it from [[Alexandria]]. However, it was visible from [[Aswan|Syene]] in the time of the Almagest.

The first star atlas to contain Achernar in the chart of Eridanus is [[Johann Bayer]]'s ''[[Uranometria]]''.<ref name=ridpath/> Bayer did not observe it himself, and the first European knowledge of it is attributed to [[Pieter Dirkszoon Keyser]] on the first voyage of the Dutch to the East Indies ("[[Eerste Schipvaart]]"). Thus it was the only first-magnitude star not listed in Ptolemy's ''[[Almagest]]''.<ref name=ridpath/>

Alpha Eridani will continue to move north in the next few millennia, reaching its maximum northern declination between the 8th and 11th millennia, when it will be visible as far north as [[Germany]] and southern [[England]].{{citation needed|date=April 2018}}

==Notes==
{{reflist|group=nb}}

==References==
{{reflist|30em|refs=

<ref name=danfs>{{cite web |url=https://www.history.navy.mil/research/histories/ship-histories/danfs/a/achernar.html |title=Achernar |website=[[Dictionary of American Naval Fighting Ships]] |access-date=2023-07-14 }}</ref>

<ref name=neuhauser>{{Cite journal |last1=R. |first1=Neuhäuser |last2=G. |first2=Torres |last3=M. |first3=Mugrauer |last4=L. |first4=Neuhäuser, D. |last5=J. |first5=Chapman |last6=D. |first6=Luge |last7=Matteo |first7=Cosci |date=2022 |title=Colour evolution of Betelgeuse and Antares over two millennia, derived from historical records, as a new constraint on mass and age |url=https://hdl.handle.net/10278/5003332 |journal=Monthly Notices of the Royal Astronomical Society |language=it |volume=516 |issue=1 |doi=10.1093/mnra |doi-broken-date=11 July 2025 |hdl=10278/5003332 |issn=0035-8711}}</ref>

<ref name=balona2020>{{cite journal |bibcode=2020MNRAS.493.2528B |title=TESS observations of be stars: A new interpretation |last1=Balona |first1=L. A. |last2=Ozuyar |first2=D. |journal=Monthly Notices of the Royal Astronomical Society |year=2020 |volume=493 |issue=2 |page=2528 |doi=10.1093/mnras/staa389 |doi-access=free |arxiv=1911.03068 }}</ref>

<ref name=MAST>{{cite web |title=MAST: Barbara A. Mikulski Archive for Space Telescopes |url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html |publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>

<ref name=kervella>{{cite journal |last1=Kervella |first1=Pierre |title=The binary system of the spinning-top Be star Achernar |journal=Astronomy & Astrophysics |date=15 November 2022 |volume=667 |issue=667 |page=A111 |doi=10.1051/0004-6361/202244009 |arxiv=2209.07537 |bibcode=2022A&A...667A.111K |s2cid=252025183 }}</ref>

<ref name=aaa323_L49>{{cite journal | last1=Perryman | first1=M. A. C. | last2=Lindegren | first2=L. | last3=Kovalevsky | first3=J. |  display-authors=etal | title=The Hipparcos Catalogue | journal=Astronomy and Astrophysics | volume=323 |date=July 1997 | pages=L49–L52 | bibcode=1997A&A...323L..49P}}</ref>

<ref name=aaa474_2_653>{{cite journal | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref>

<ref name=aaaa601_a118>{{cite journal | last1=Dalla Vedova | first1=G. | last2=Millour | first2=F. | last3=Domiciano de Souza | first3=A. | last4=Petrov | first4=R. G. | last5=Moser Faes | first5=D. | last6=Carciofi | first6=A. C. | last7=Kervella | first7=P. | last8=Rivinius | first8=T. | title=VLTI/PIONIER images the Achernar disk swell | journal=Astronomy and Astrophysics | volume=601 | page=1 | date=May 2017 | doi=10.1051/0004-6361/201628230 | bibcode=2017A&A...601A.118D |arxiv = 1703.02839 | s2cid=54791255 }}</ref>

<ref name=rgcrv>{{cite conference | last=Evans | first=D. S. | date=June 20–24, 1966 | editor=Batten, Alan Henry | editor2=Heard, John Frederick | title=The Revision of the General Catalogue of Radial Velocities | book-title=Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30 | location=University of Toronto | publisher=International Astronomical Union | bibcode=1967IAUS...30...57E }}</ref>

<ref name=GSM>{{cite book | last=Perryman | first=Michael | title=The Making of History's Greatest Star Map | location=Heidelberg | publisher=Springer-Verlag | date=2010 | doi=10.1007/978-3-642-11602-5| series=Astronomers’ Universe | isbn=978-3-642-11601-8 | bibcode=2010mhgs.book.....P | url=https://cds.cern.ch/record/1338896 }}</ref>

<ref name="SIMBAD">{{cite web | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=HIP7588 | title=Achernar -- Be Star | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | access-date=2010-02-16 }}</ref>

<ref name=aaa484_1_L13>{{cite journal | last1=Kervella | first1=P. | last2=Domiciano de Souza | first2=A. | last3=Bendjoya | first3=Ph. | title=The close-in companion of the fast rotating Be star Achernar | journal=Astronomy and Astrophysics | volume=484 | issue=1 | pages=L13–L16 |date=June 2008 | doi=10.1051/0004-6361:200809765 | bibcode=2008A&A...484L..13K |arxiv = 0804.3465 | s2cid=1776184 }}</ref>

<ref name=aaa493_3_L53>{{cite journal | display-authors=1 | last1=Kervella | first1=P. | last2=Domiciano de Souza | first2=A. | last3=Kanaan | first3=S. | last4=Meilland | first4=A. | last5=Spang | first5=A. | last6=Stee | first6=Ph. | title=The environment of the fast rotating star Achernar. II. Thermal infrared interferometry with VLTI/MIDI | journal=Astronomy and Astrophysics | volume=493 | issue=3 | pages=L53–L56 |date=January 2009 | doi=10.1051/0004-6361:200810980 | bibcode=2009A&A...493L..53K |arxiv = 0812.2531 | s2cid=9224250 }}</ref>
\
<ref name=apj671_1_L49>{{cite journal | display-authors=1 | last1=Carciofi | first1=A. C. | last2=Magalhães | first2=A. M. | last3=Leister | first3=N. V. | last4=Bjorkman | first4=J. E. | last5=Levenhagen | first5=R. S. | title=Achernar: Rapid Polarization Variability as Evidence of Photospheric and Circumstellar Activity | journal=The Astrophysical Journal | volume=671 | issue=1 | pages=L49–L52 |date=December 2007 | doi=10.1086/524772 | bibcode=2007ApJ...671L..49C |arxiv = 0710.4163 | s2cid=16106929 }}</ref>

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<ref name=ducati>{{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}}</ref>

<ref name=gcvs>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|pages=02025|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|date=2009|display-authors=etal}}</ref>

<ref name="IAU-LSN">{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars | publisher=IAU.org | access-date=16 December 2017 | archive-date=10 March 2025 | archive-url=https://web.archive.org/web/20250310063743/https://www.iau.org/public/themes/naming_stars/ | url-status=dead }}</ref>

<ref name="planetnaming">{{cite arXiv |title=On the naming convention used for multiple star systems and extrasolar planets |date=2010 |eprint=1012.0707 |class=astro-ph.SR |last1= Hessman |first1=F. V. |last2= Dhillon |first2=V. S. |last3= Winget |first3=D. E. |last4= Schreiber |first4=M. R. |last5= Horne |first5=K. |last6= Marsh |first6=T. R. |last7= Guenther |first7=E. |last8= Schwope |first8=A. |last9= Heber |first9=U. }}</ref>

<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN) | access-date=22 May 2016 | archive-date=10 June 2016 | archive-url=https://web.archive.org/web/20160610172014/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead }}</ref>

<ref name="TriRpt18">{{cite web | url=https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf | page=5 | title=WG Triennial Report (2015-2018) - Star Names | access-date=2018-07-14 | archive-date=2022-10-09 | archive-url=https://ghostarchive.org/archive/20221009/https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf | url-status=dead }}</ref>

<ref name=aeea>{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0607/ap060727.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 27 日] {{Webarchive|url=https://web.archive.org/web/20110522003318/http://aeea.nmns.edu.tw/2006/0607/ap060727.html |date=2011-05-22 }}</ref>

<ref name="hamacher">{{Cite journal |last1=Hamacher |first1=Duane W. |last2=Frew |first2=David J. |date=2010-11-01 |title=An Aboriginal Australian Record of the Great Eruption of Eta Carinae |journal=Journal of Astronomical History and Heritage |language=en |volume=13 |issue=3 |pages=220–234 |arxiv=1010.4610 |bibcode=2010JAHH...13..220H |doi=10.3724/SP.J.1440-2807.2010.03.06 |issn=1440-2807 |s2cid=118454721}}</ref>

<ref name=kong2015>{{cite journal |bibcode=2015MNRAS.448..456K |title=An exact solution for arbitrarily rotating gaseous polytropes with index unity |last1=Kong |first1=Dali |last2=Zhang |first2=Keke |last3=Schubert |first3=Gerald |journal=Monthly Notices of the Royal Astronomical Society |year=2015 |volume=448 |issue=1 |page=456 |doi=10.1093/mnras/stu2759 |doi-access=free |hdl=10871/16779 |hdl-access=free }}</ref>

<ref name=cotton>{{cite journal | title=The linear polarization of Southern bright stars measured at the parts-per-million level | last=Cotton | first=D. V. |  display-authors=etal | journal=Monthly Notices of the Royal Astronomical Society | volume=455 | issue=2 | pages=1607–1628 |date=January 2016 | bibcode=2016MNRAS.455.1607C |doi=10.1093/mnras/stv2185 | doi-access=free |arxiv=1509.07221 | s2cid=11191040 }}</ref>

<ref name=souza2014>{{cite journal |bibcode=2014A&A...569A..10D |title=The environment of the fast rotating star Achernar. III. Photospheric parameters revealed by the VLTI |last1=Domiciano De Souza |first1=A. |last2=Kervella |first2=P. |last3=Moser Faes |first3=D. |last4=Dalla Vedova |first4=G. |last5=Mérand |first5=A. |last6=Le Bouquin |first6=J. -B. |last7=Espinosa Lara |first7=F. |last8=Rieutord |first8=M. |last9=Bendjoya |first9=P. |last10=Carciofi |first10=A. C. |last11=Hadjara |first11=M. |last12=Millour |first12=F. |last13=Vakili |first13=F. |journal=Astronomy and Astrophysics |year=2014 |volume=569 |pages=A10 |doi=10.1051/0004-6361/201424144 |doi-access=free }}</ref>

<ref name="Stellarium">Calculated by [[Stellarium (software)|Stellarium]] 0.13</ref>

<ref name=ridpath>{{cite web|url=http://www.ianridpath.com/startales/eridanus.html#achernar | title=Ian Ridpath - Star Tales – Eridanus|access-date=2017-01-13}}</ref>

<ref name="allen">{{Cite book |last=Allen |first=Richard Hinckley |url=https://books.google.com/books?id=l8V2DY3tQMgC |title=Star Names: Their Lore and Meaning |date=1963 |publisher=Courier Corporation |isbn=978-0-486-21079-7 |language=en}}</ref>

<ref name="reverso_context">{{cite web|url=https://context.reverso.net/translation/arabic-english/%D8%A2%D8%AE%D8%B1+%D8%A7%D9%84%D9%86%D9%87%D8%B1| title=Reverso Context - آخر النهر|access-date=2022-12-28}}</ref>

<ref name=Gould1879>{{citation
 | url=http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=V%2F135%2Fcatalog
 | last=Gould | first=Benjamin Apthorp | date=1879
 | title=Uranometria Argentina catalog of bright southern stars
 | journal=Resultados del Observatorio Nacional Argentino en Cordoba
 | volume=1 | publication-place=Buenos Aires
 | bibcode=1879RNAO....1.....G | access-date=2012-05-08
}}</ref>

<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=13 November 2025}}</ref>

}}

==Further reading==
* {{cite journal|bibcode=2006ApJ...643..460L|arxiv=astro-ph/0602084|title=Surface Temperature and Synthetic Spectral Energy Distributions for Rotationally Deformed Stars|journal=The Astrophysical Journal|volume=643|issue=1|pages=460–470|last1=Lovekin|first1=C. C.|last2=Deupree|first2=R. G.|last3=Short|first3=C. I.|year=2006|doi=10.1086/501492|s2cid=17998437}}

{{Sky|01|37|42.8|-|57|14|12|144}}

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

<!-- Properties -->

{{DEFAULTSORT:Achernar}}
[[Category:B-type main-sequence stars]]
[[Category:Be stars]]
<!-- Position/Catalogues -->
[[Category:Eridanus (constellation)]]
[[Category:Bayer objects|Eridani, Alpha]]
[[Category:Bright Star Catalogue objects|0472]]
[[Category:Durchmusterung objects|CD-57 00316]]
[[Category:Henry Draper Catalogue objects|010144]]
[[Category:Hipparcos objects|007588]]
[[Category:Southern pole stars]]
[[Category:Stars with proper names|Achernar]]
[[Category:Lucidae]]