Editing Eta Canis Majoris

{{short description|Star in the constellation Canis Major}}
{{Starbox begin
| name=η Canis Majoris
}}
{{Starbox image
 | image=
{{Location mark
|image=Canis Major constellation map.svg|alt=|float=center|width=240
|label=|position=right
|mark=Red circle.svg|mark_width=12|mark_link=η CMa
|x=77|y=852
}}
|caption=Location of η Canis Majoris (circled)
}}
{{Starbox observe
| epoch = J2000
| ra = {{RA|07|24|05.70228}}<ref name=aaa474_2_653/>
| dec = {{DEC|-29|18|11.1798}}<ref name=aaa474_2_653/>
| appmag_v = 2.38{{snd}}2.48<ref name=Kazarovets/>
| constell = [[Canis Major]]
}}
{{Starbox character
| type = [[Blue supergiant]], likely a post-[[red supergiant]]<ref name=Sanchez2023/>
| class = B5&nbsp;Ia<ref name=aaa521/>
| b-v = −0.087<ref name=apj156_853/>
| u-b = −0.708<ref name=apj156_853/>
| variable = [[Alpha Cygni variable|α Cyg]]<ref name=Kazarovets/>
}}
{{Starbox astrometry
| radial_v = 41.1<ref name=scfs/>
| prop_mo_ra = −4.14<ref name=aaa474_2_653/>
| prop_mo_dec = 5.81<ref name=aaa474_2_653/>
| parallax = 1.64
| p_error = 0.40
| parallax_footnote = <ref name=aaa474_2_653/>
| absmag_v = −7.0<ref name=mnras189_601/>
}}
{{Starbox detail
| mass = 5.5 or 9.5<ref name=Sanchez2023/>
| temperature = {{Val|15800|100|400|fmt=commas}}<ref name=Sanchez2023/>
| radius = 54<ref name=haucke2018/>
| luminosity = {{val|163800|4200|15900|fmt=commas}}<ref name=Sanchez2023/>
| gravity = {{val|1.95|0.02|0.03}}<ref name=haucke2018/>
| rotational_velocity = {{Val|51.5|5.0}}<ref name=Sanchez2023/>
| age_myr = 8.3<ref name=tetzlaff2011/>
}}
{{Starbox catalog
| names=Aludra, 31&nbsp;Canis Majoris, [[Cordoba Durchmusterung|CD]]−29°4328, [[FK5]]&nbsp;283, [[Henry Draper Catalogue|HD]]&nbsp;58350, [[Hipparcos catalogue|HIP]]&nbsp;35904, [[Bright Star Catalogue|HR]]&nbsp;2827, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;173651
}}
{{Starbox reference
| Simbad=HD+58350
}}
{{Starbox end}}

'''Eta Canis Majoris''' ('''η Canis Majoris''', abbreviated '''Eta CMa''', '''η CMa'''), also named '''Aludra''' {{IPAc-en|ə|'|l|uː|d|r|ə|,_|ə|'|lj|uː|d|r|ə}},<ref name="IAU-CSN">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref> is a [[star]] in the [[constellation]] of [[Canis Major]]. Since 1943, the [[stellar spectrum|spectrum]] of this star has served as one of the stable anchor points by which other stars are classified.<ref name=baas25_1319/>

== Nomenclature==
''η Canis Majoris'' ([[Latinisation of names|Latinised]] to ''Eta Canis Majoris'') is the star's [[Bayer designation]].

The traditional name ''Aludra'' originates from the [[Arabic]]: ''العذراء'' ''al-adhraa'', 'the virgin'. This star, along with [[Epsilon Canis Majoris]] (Adhara), [[Delta Canis Majoris]] (Wezen) and [[Omicron2 Canis Majoris|Omicron<sup>2</sup> Canis Majoris]] (Thanih al Adzari), were ''Al 'Adhārā'' (''العذاري''), 'the Virgins'.<ref name=allen1963/> In 2016, the [[International Astronomical Union]] organized a [[Working Group on Star Names]] (WGSN)<ref name="WGSN"/> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1"/> included a table of the first two batches of names approved by the WGSN; which included ''Aludra'' for this star.

In [[Chinese language|Chinese]], {{lang|zh|弧矢}} ({{lang|zh-Latn|Hú Shǐ}}), meaning ''[[Well (Chinese constellation)|Bow and Arrow]]'',<ref name=KooShe/> refers to an [[Asterism (astronomy)|asterism]] consisting of Eta Canis Majoris, [[Delta Canis Majoris]], [[HD 63032]], [[HD 65456]], [[Omicron Puppis]], [[k Puppis]], [[Epsilon Canis Majoris]], [[Kappa Canis Majoris]] and [[Pi Puppis]]. Consequently, Eta Canis Majoris itself is known as {{lang|zh|弧矢二}} ({{lang|zh-Latn|Hú Shǐ èr}}, {{langx|en|the Second Star of Bow and Arrow}}).<ref name=AEEA/>

==Properties==
[[File:EtaCMaLightCurve.png|thumb|left|A [[light curve]] for Eta Canis Majoris, plotted from ''[[Hipparcos]]'' data<ref name=HIPCurve/>]]

Eta Canis Majoris is a [[blue supergiant]] with a [[spectral type]] B5Ia. It has been the standard for this spectral class in the [[Morgan–Keenan system]].<ref name=morgan1978/> It is likely a post-[[red supergiant]], a star which left its [[red supergiant]] phase and near the end of its life. As a consequence, Eta CMa has [[stellar mass loss|lost]] significant part of its mass, and now has a mass of either {{solar mass|5.5 or 9.5}}, depending on the estimate, in contrast with its initial mass of {{solar mass|22}}.<ref name=Sanchez2023/>

Eta CMa shines brightly in the skies in spite of a large distance from [[Earth]] due to being [[absolute magnitude|intrinsically many times brighter]] than the [[Sun]]. It has a luminosity over 100,000 times and a radius around 54 times that of the Sun. It has only existed for a fraction of the time the Sun has, less than 10 million years, yet is already in the last stages of its life.<ref name=haucke2018/><ref name=Sanchez2023/>

Eta CMa is classified as an [[Alpha Cygni variable|Alpha Cygni-type]] [[variable star]] and its brightness varies from magnitude +2.38 to +2.48 over a period of 4.7 days.<ref name=Kazarovets/><ref name=AAVSOeta/>

==Namesakes==
Both [[USS Aludra (AF-55)|USS ''Aludra'' (AF-55)]], an [[Type R ship|''Alstede''-class]] [[stores ship]], and [[USS Aludra (AK-72)|USS ''Aludra'' (AK-72)]], a [[Crater-class cargo ship|''Crater''-class cargo ship]], were [[U.S. Navy]] vessels named after the star.

==References==
{{reflist|refs=

<ref name=morgan1978>{{cite book|bibcode=1978rmsa.book.....M|year=1978|title=Revised MK Spectral Atlas for stars earlier than the sun|last1=Morgan|first1=W. W.|last2=Abt|first2=Helmut A.|last3=Tapscott|first3=J. W.|publisher=Yerkes Observatory, University of Chicago, and Kitt Peak National Observatory}}</ref>

<!-- <ref name=kervella2022>{{cite journal |bibcode=2022A&A...657A...7K |title=Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs |last1=Kervella |first1=Pierre |last2=Arenou |first2=Frédéric |last3=Thévenin |first3=Frédéric |journal=Astronomy and Astrophysics |year=2022 |volume=657 |page=657 |doi=10.1051/0004-6361/202142146 |arxiv=2109.10912 |s2cid=237605138 }}</ref> -->

<ref name=Sanchez2023>{{Cite journal |last1=Sánchez Arias |first1=Julieta Paz |last2=Németh |first2=Péter |last3=de Almeida |first3=Elisson Saldanha da Gama |last4=Ruiz Diaz |first4=Matias Agustin |last5=Kraus |first5=Michaela |last6=Haucke |first6=Maximiliano |date=2023-08-01 |title=Unveiling the Evolutionary State of Three B Supergiant Stars: PU Gem, ϵ CMa, and η CMa |bibcode=2023Galax..11...93S |arxiv=2308.12745 |journal=Galaxies |volume=11 |issue=5 |pages=93 |doi=10.3390/galaxies11050093|doi-access=free }}</ref>

<ref name=tetzlaff2011>{{cite journal
 | display-authors=1 | last1=Tetzlaff | first1=N.
 | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M.
 | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun
 | journal=[[Monthly Notices of the Royal Astronomical Society]]
 | volume=410 | issue=1 | pages=190–200 | date=January 2011
 | doi=10.1111/j.1365-2966.2010.17434.x | doi-access=free | bibcode=2011MNRAS.410..190T
 | arxiv=1007.4883 | s2cid=118629873 }}</ref>

<ref name=haucke2018>{{cite journal |bibcode=2018A&A...614A..91H |title=Wind properties of variable B supergiants. Evidence of pulsations connected with mass-loss episodes |last1=Haucke |first1=M. |last2=Cidale |first2=L. S. |last3=Venero |first3=R. O. J. |last4=Curé |first4=M. |last5=Kraus |first5=M. |last6=Kanaan |first6=S. |last7=Arcos |first7=C. |journal=Astronomy and Astrophysics |year=2018 |volume=614 |doi=10.1051/0004-6361/201731678 |arxiv=1902.01341 |s2cid=126150688 }}</ref>

<ref name=AAVSOeta>{{cite web
 | url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=5506
 | title=Eta Canis Majoris |author =Watson, Christopher |date=3 May 2013
 | work=AAVSO Website|publisher=[[American Association of Variable Star Observers]]
 | access-date=5 February 2014}}</ref>

<ref name="WGSN1">{{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}}</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}}</ref>

<ref name=HIPCurve>{{cite web |title=Light Curve |url=https://www.cosmos.esa.int/web/hipparcos/java-tools/light-curve |website=Hipparcos ESA |publisher=ESA |access-date=12 August 2022}}</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=aaa521>{{citation | last1=Prinja | first1=R. K. | last2=Massa | first2=D. L. | title=Signature of wide-spread clumping in B supergiant winds | journal=Astronomy and Astrophysics | volume=521 | pages=L55 |date=October 2010 | doi=10.1051/0004-6361/201015252 | bibcode=2010A&A...521L..55P |arxiv = 1007.2744 | s2cid=59151633 }}</ref>

<ref name=apj156_853>{{citation | last1=Alcaino | first1=Gonzalo | title=The Globular Clusters NGC 2808 and NGC 1851 | journal=Astrophysical Journal | volume=156 | page=853 |date=June 1969 | doi=10.1086/150019 | bibcode=1969ApJ...156..853A }}</ref>

<ref name=allen1963>{{citation | last=Allen | first=R. H. | date=1963 | author-link=Richard Hinckley Allen | title=Star Names: Their Lore and Meaning | url=https://archive.org/details/starnamestheirlo00alle/page/130 | access-date=2010-12-12 | edition=Reprint | publisher=Dover Publications Inc | location=New York, NY | isbn=((0-486-21079-0)) | page=[https://archive.org/details/starnamestheirlo00alle/page/130 130] | url-access=registration }}</ref>

<ref name=AEEA>{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0607/ap060717.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日] {{Webarchive|url=https://web.archive.org/web/20120204114243/http://aeea.nmns.edu.tw/2006/0607/ap060717.html |date=2012-02-04 }}</ref>

<ref name=KooShe>弧矢 (Hú Shǐ) is westernized into ''Koo She''. R.H. Allen had opinion that ''Koo She'' refers to the [[Asterism (astronomy)|asterism]] including [[Delta Velorum]] and [[Omega Carinae]]. AEEA opinion is, Delta Velorum is member of {{lang|zh|天社}} ({{lang|zh-Latn|Tiān Shè}}), meaning ''[[Well (Chinese constellation)|Celestial Earth God's Temple]]'' asterism, and Omega Carinae is not member of any asterisms. 天社 (Tiān Shè) is westernized into ''Tseen She'' and R.H. Allen used the term ''Tseen She'' for Chinese name of [[Eta Carinae]]. See [https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Argo_Navis*.html Richard Hinckley Allen: Star Names — Their Lore and Meaning: Argo Navis] and {{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0607/ap060717.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 17 日] {{Webarchive|url=https://web.archive.org/web/20120204114243/http://aeea.nmns.edu.tw/2006/0607/ap060717.html |date=2012-02-04 }}.</ref>

<ref name=Kazarovets>{{cite journal|bibcode=1999IBVS.4659....1K|title=The 74th Special Name-list of Variable Stars|journal=Information Bulletin on Variable Stars|volume=4659|pages=1|last1=Kazarovets|first1=E. V.|last2=Samus|first2=N. N.|last3=Durlevich|first3=O. V.|last4=Frolov|first4=M. S.|last5=Antipin|first5=S. V.|last6=Kireeva|first6=N. N.|last7=Pastukhova|first7=E. N.|year=1999}}</ref>

<ref name=scfs>{{cite journal | display-authors=1 | title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions | journal=Veröff. Astron. Rechen-Inst. Heidelb | volume=35 | last1=Wielen | first1=R. | last2=Schwan | first2=H. | last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H. | last5=Jahreiß | first5=H. | last6=Jährling | first6=R. | publisher=Astronomisches Rechen-Institut Heidelberg | issue=35 | pages=1 | date=1999 | bibcode=1999VeARI..35....1W }}</ref>

<ref name=baas25_1319>{{cite journal | last1=Garrison | first1=R. F. | title=Anchor Points for the MK System of Spectral Classification | journal=Bulletin of the American Astronomical Society | volume=25 | page=1319 | date=December 1993 | bibcode=1993AAS...183.1710G | url=http://www.astro.utoronto.ca/~garrison/mkstds.html | access-date=2012-02-04 | archive-date=2019-06-25 | archive-url=https://web.archive.org/web/20190625094716/http://www.astro.utoronto.ca/~garrison/mkstds.html | url-status=dead }}</ref>

<ref name=mnras189_601>{{cite journal| display-authors=1 | last1=Underhill | first1=A. B. | last2=Divan | first2=L. | last3=Prevot-Burnichon | first3=M.-L. | last4=Doazan | first4=V. | title=Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=189 | issue=3 | pages=601–605 |date=November 1979 | bibcode=1979MNRAS.189..601U | doi=10.1093/mnras/189.3.601| doi-access=free }}</ref>
}}

{{Stars of Canis Major}}

{{Authority control}}

{{DEFAULTSORT:Eta Canis Majoris}}
[[Category:Alpha Cygni variables]]
[[Category:Bayer objects|Canis Majoris, Eta]]
[[Category:B-type supergiants]]
[[Category:Canis Major]]
[[Category:Flamsteed objects|Canis Majoris, 31]]
[[Category:Henry Draper Catalogue objects|058350]]
[[Category:Hipparcos objects|035904]]
[[Category:Stars with proper names|Aludra]]
[[Category:Bright Star Catalogue objects|2827]]
[[Category:Durchmusterung objects|CD-29 04328]]