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pipe "Alcor" to Alcor (star) and "whole system" to Mizar and Alcor
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{{Starbox begin
{{Starbox begin
| name=Mizar
| name=Mizar
}}
{{Starbox image
| image=
{{Location mark
⚫
|image=Ursa Major constellation map.svg|alt=|float=center|width=260
|label=|position=right
|mark=Red circle.svg|mark_width=10
|x=205|y=410
}}
|caption=Location of Mizar (circled)
}}
}}
{{Starbox observe 3s
{{Starbox observe 3s
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| ra1 = {{RA|13|23|55.54048}}<ref name=hipparcos/>
| ra1 = {{RA|13|23|55.54048}}<ref name=hipparcos/>
| dec1 = {{DEC|+54|55|31.2671}}<ref name=hipparcos/>
| dec1 = {{DEC|+54|55|31.2671}}<ref name=hipparcos/>
| appmag_v1 = 2.27<ref name=hipparcos/>
| appmag_v1 = 2.04<ref name=eggletonubv/>
| component2 = ζ<sup>1</sup> UMa
| component2 = ζ<sup>1</sup> UMa
| ra2 = {{RA|13|23|55.543}}<ref name=tycho/>
| ra2 = {{RA|13|23|55.543}}<ref name=tycho/>
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| variable=
| variable=
| component2 = ζ<sup>2</sup> UMa
| component2 = ζ<sup>2</sup> UMa
| class2=A3m<ref name=jaschek/>{{nowrap|(kA2hA6mA6<ref name=abt/>)}}
| class2= kA1h(eA)mA7IV-V<ref name=gray/>
| b-v2 = +0.13<ref name=ubv/>
| b-v2 = +0.13<ref name=ubv/>
| u-b2 = +0.09<ref name=ubv/>
| u-b2 = +0.09<ref name=ubv/>
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}}
}}
{{Starbox orbit
{{Starbox orbit
|reference=<ref name=Hummel/>
|reference=
|primary=Mizar Aa
|primary=Mizar Aa
|name=Mizar Ab
|name=Mizar Ab
|axis_unitless=9.83 ± 0.03 mas
|axis={{val|9.83|0.03}}<ref name=Hummel/>
|inclination=60.5 ± 0.3
|inclination={{val|60.5|0.3}}<ref name=behr/>
|node=106.0 ± 0.4
|node={{val|106.0|0.4}}<ref name=Hummel/>
|periastron=[[Julian date|JD]] 2447636.07 ± 0.02
|periastron=[[Reduced Julian date|RJD]] 54536.9904<ref name=behr/>
|eccentricity=0.5354 ± 0.0025
|eccentricity={{val|0.5415|0.0016}}<ref name=behr/>
|periarg=104.3 ± 0.3
|periarg={{val|105.27|0.23}}<ref name=behr/>
|period_unitless=20.53835 ± 0.00005 d
|period_unitless=20.5386 days<ref name=behr/>
|k1={{val|66.478|0.153}}<ref name=behr/>
|k1=69.1
|k2={{val|66.019|0.177}}<ref name=behr/>
|k2=67.2
}}
}}
{{Starbox orbit
{{Starbox orbit
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}}
}}
{{Starbox detail
{{Starbox detail
| component1=Mizar Aa
| component1 = Mizar Aa
| mass=2.43 ± 0.07<ref name=Hummel/>
| mass = {{val|2.2224|0.0221}}<ref name=behr/>
| temperature=9000 ± 200<ref name=Hummel/>
| temperature = 9,000 ± 200<ref name=Hummel/>
| luminosity=33.3 ± 2.1<ref name=Hummel/>
| luminosity = 33.3 ± 2.1<ref name=Hummel/>
| radius=2.4 ± 0.1<ref name=Hummel/>
| radius = 2.4 ± 0.1<ref name=Hummel/>
| age_myr = 370<ref name=thureau/>
| component2=Mizar Ab
| component2 = Mizar Ab
⚫
| mass2=2.50 ± 0.07<ref name=Hummel/>
| temperature2=9000 ± 200<ref name=Hummel/>
| mass2 = {{val|2.2381|0.0219}}<ref name=behr/>
| luminosity2=33.3 ± 2.1<ref name=Hummel/>
| temperature2 = 9,000 ± 200<ref name=Hummel/>
⚫
| luminosity2 = 33.3 ± 2.1<ref name=Hummel/>
| radius2=2.4 ± 0.1<ref name=Hummel/>
| radius2=2.4 ± 0.1<ref name=Hummel/>
}}
}}
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{{Starbox end}}
{{Starbox end}}


'''Mizar''' a star in the handle of the [[Big Dipper]] [[Asterism (astronomy)|asterism]] in the constellation of [[Ursa Major]]. It is also designated '''ζ&nbsp;Ursae Majoris''' ([[Latinised]] as '''Zeta Ursae Majoris'''). It forms a well-known naked eye [[double star]] with the fainter star [[Mizar and Alcor|Alcor]], and is itself a [[Star system|quadruple star system]]. The whole system lies about 83 light-years away from the [[Sun]], as measured by the [[Hipparcos]] astrometry satellite.
'''Mizar''' is a 2nd [[apparent magnitude|magnitude]] star in the handle of the [[Big Dipper]] [[Asterism (astronomy)|asterism]] in the constellation of [[Ursa Major]]. It has the [[Bayer designation]] '''ζ&nbsp;Ursae Majoris''' ([[Latinised]] as '''Zeta Ursae Majoris'''). It forms a well-known naked eye [[double star]] with the fainter star [[Alcor (star)|Alcor]], and is itself a [[Star system|quadruple star system]]. The [[Mizar and Alcor|whole system]] lies about 83 light-years away from the [[Sun]], as measured by the [[Hipparcos]] astrometry satellite, and is part of the [[Ursa Major Moving Group]].


==Nomenclature==
==Nomenclature==
''ζ&nbsp;Ursae Majoris'' ([[Latinisation of names|Latinised]] to ''Zeta Ursae Majoris'' and abbreviated to ζ&nbsp;UMa or Zeta&nbsp;UMa) is Mizar's [[Bayer designation]]. It also has the [[Flamsteed designation]] 79 Ursae Majoris.
''ζ&nbsp;Ursae Majoris'' ([[Latinisation of names|Latinised]] to ''Zeta Ursae Majoris'' and abbreviated to ζ&nbsp;UMa or Zeta&nbsp;UMa) is Mizar's [[Bayer designation]]. It also has the [[Flamsteed designation]] 79 Ursae Majoris.


The traditional name ''Mizar'' derives from the [[Arabic]] ''{{lang|ar|{{large|المئزر}}}}'' ''{{transl|ar|ALA|miʼzar}}'' meaning 'apron; wrapper, covering, cover'.<ref name=wehr/> In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name=WGSN/> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name=WGSN1/> included a table of the first two batches of names approved by the WGSN; which included ''Mizar'' for ζ&nbsp;UMa. According to IAU rules, the name Mizar strictly only applies to component Aa.<ref name="IAU-CSN"/>
The traditional name ''Mizar'' derives from the [[Arabic]] ''{{lang|ar|{{large|المئزر}}}}'' ''{{transl|ar|ALA|miʼzar}}'' meaning 'apron; wrapper, covering, cover'.<ref name=wehr/> In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name=WGSN/> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name=WGSN1/> included a table of the first two batches of names approved by the WGSN; which included ''Mizar'' for ζ&nbsp;UMa. According to IAU rules, the name Mizar strictly only applies to component Aa,<ref name="IAU-CSN"/> although it is traditionally and popularly used for all four stars making up the single naked-eye star.<ref name=allen/><ref name=consolmagno/>


==Stellar system==
==Stellar system==
⚫
[[File:BigdipISS.jpg|thumb|left|upright=1.2|The [[Big Dipper]]'s bowl and part of the handle photographed from the [[International Space Station]]. Mizar and Alcor are at the upper right.]]
Mizar is a visual [[double star|double]] with a separation of 14.4 arcseconds, each of which is a [[spectroscopic binary]]. Its apparent [[Magnitude (astronomy)|magnitude]] is 2.23 and its spectral class is A2V. The two visible stars are referred to as ζ<sup>1</sup> and ζ<sup>2</sup> Ursae Majoris, or Mizar A and B. The spectroscopic components are generally referred to as Mizar Aa, Ab, Bb, and Bb.
Mizar is a visual [[double star|double]] with a separation of 14.4 arcseconds, each of which is a [[spectroscopic binary]]. Its combined apparent [[Magnitude (astronomy)|magnitude]] is 2.04. The two visible stars are referred to as ζ<sup>1</sup> and ζ<sup>2</sup> Ursae Majoris, or Mizar A and B. The spectroscopic components are generally referred to as Mizar Aa, Ab, Ba, and Bb. The stars all share a single [[Hipparcos]] designation of HIP 65378, but separate [[Bright Star Catalogue]] and [[Henry Draper Catalogue]] entries. Mizar, together with Alcor and many of the other bright stars in Ursa Major, is a member of the [[Ursa Major Moving Group]].<ref name=jones/>


An easily split visual target, Mizar was the first telescopic binary discovered, most probably by [[Benedetto Castelli]] who in 1617 asked [[Galileo Galilei]] to observe it. Galileo then produced a detailed record of the double star. Later, around 1650, [[Giovanni Battista Riccioli|Riccioli]] wrote of Mizar appearing as a double. The secondary star (designated Mizar B) has magnitude 4.0 and spectral class A7, and comes within 380 [[Astronomical unit|AU]] of the primary (Mizar A); the two take thousands of years to revolve around each other.
An easily split visual target, Mizar was the first telescopic binary discovered, most probably by [[Benedetto Castelli]] who in 1617 asked [[Galileo Galilei]] to observe it. Galileo then produced a detailed record of the double star.<ref name="Marett-Crosby2013"/> Later, around 1650, [[Giovanni Battista Riccioli|Riccioli]] wrote of Mizar appearing as a double.<ref name=dick/> The secondary star (Mizar B) comes within 380 [[Astronomical unit|AU]] of the primary (Mizar A) and the two take thousands of years to revolve around each other.<ref name=burnham/>


Mizar A was the first [[spectroscopic binary]] to be discovered, by [[Edward Charles Pickering|Pickering]] in 1889. Some spectroscopic binaries cannot be visually resolved and are discovered by studying the spectral lines of the suspect system over a long period of time. The two components of Mizar A are both about 35 times as bright as the Sun, and revolve around each other in about 20 days 12 hours and 55 minutes. Mizar B was later found to be a spectroscopic binary as well, its components completing an orbital period every six months. In 1996, 107 years after their discovery, the components of the Mizar A binary system were imaged in extremely high resolution using the [[Navy Prototype Optical Interferometer]].<ref name=benson/>
Mizar A was the first [[spectroscopic binary]] to be discovered, as part of [[Antonia Maury]]'s spectral classification work, and an orbit was published in 1890. Some spectroscopic binaries cannot be visually resolved and are discovered by studying the spectral lines of the suspect system over a long period of time. The two components of Mizar A are both about 35 times as bright as the Sun, and revolve around each other in about 20 days 12 hours and 55 minutes. In 1908, Mizar B was also found to be a spectroscopic binary, its components completing an orbital period every six months.<ref name=mamajek/> In 1996, 107 years after their discovery, the components of the Mizar A binary system were imaged in extremely high resolution using the [[Navy Prototype Optical Interferometer]].<ref name=benson/>


===ζ<sup>1</sup> Ursae Majoris===
<gallery widths="250px" heights="150px">
[[File:Mizar-A-BS2.png|thumb|left|upright=1.2|[[Radial velocity]] curves for the two almost identical components]]
⚫
File:BigdipISS.jpg|The Big Dipper's bowl and part of the handle photographed from the [[International Space Station]]. Mizar and Alcor are at the upper right.
The two components of ζ<sup>1</sup> Ursae Majoris (Mizar Aa and Ab) are observed to be identical, with the exception of slightly different radial velocity variations which indicate very slightly different masses.
⚫
File:Ursa Major constellation detail map.PNG|Big Dipper map

</gallery>
The spectral lines of the two stars can be observed separately and both are given a spectral type of A2Vp. They are [[Ap star]]s, chemically peculiar due to stratification of some heavy elements in the [[photosphere]] of slowly-rotating hot stars. In this case, they show elevated abundances of [[strontium]] and [[silicon]].<ref name=abt/>

With the assumption of identical physical properties for the two stars, they both have temperatures of 9,000 K, radii of {{solar radius|2.4}}, and [[bolometric luminosities]] of {{solar luminosity|33.3}}.<ref name=Hummel/> They are thought to be around 370 million years old.<ref name=thureau/>

===ζ<sup>2</sup> Ursae Majoris===
ζ<sup>2</sup> Ursae Majoris is a single-lined spectroscopic binary, and the visible spectrum is of an [[Am star]], named for their unusually strong lines of some metals. The spectral type of kA1h(eA)mA7IV-V is in a form used for metallic-lined stars: the type is A1 based on the [[calcium K line]]s, early A based on the hydrogen lines, and A7 based on lines of other metals. The luminosity class is ranked between [[main sequence]] and [[subgiant]].


==Other names==
==Other names==
Mizar is known as [[Vashistha]] one of the [[Saptarishi]], in traditional [[Indian astronomy]].<ref name=ref65zigip/> As a married couple, they are considered to symbolize marriage and in some [[Hindu]] communities to this day priests conducting a wedding ceremony allude to or point out the constellation as a symbol of the closeness marriage brings to a couple.<ref name=ref50haduv/>
Mizar is known as [[Vashistha]] one of the [[Saptarishi]], in traditional [[Indian astronomy]].<ref name=ref65zigip/>


Al-Sahja was the rhythmical form of the usual Suha. It appears as {{lang|ar|الخوّار}} ''{{transl|ar|ALA|al-Khawwar}}'', 'the Faint One', in an interesting list of [[Arabic star names]], published in ''Popular Astronomy'', January 1895, by Professor Robert H. West, of the Syrian Protestant College at Beirut.{{cn|date=December 2017}}
Al-Sahja was the rhythmical form of the usual Suha. It appears as {{lang|ar|الخوّار}} ''{{transl|ar|ALA|al-Khawwar}}'', 'the Faint One', in an interesting list of [[Arabic star names]], published in ''Popular Astronomy'', January 1895, by Professor Robert H. West, of the Syrian Protestant College at Beirut.{{citation needed|date=December 2017}}


Chinese [[Taoism]] personifies ζ Ursae Majoris as the [[Fu Lu Shou#Luxing|Lu star]].{{cn|date=December 2017}}
Chinese [[Taoism]] personifies ζ Ursae Majoris as the [[Fu Lu Shou#Luxing|Lu star]].{{citation needed|date=December 2017}}


In [[Chinese language|Chinese]], {{lang|zh|北斗}} ({{lang|zh-Latn|Běi Dǒu}}), meaning ''[[Purple Forbidden enclosure|Northern Dipper]]'', refers to an asterism consisting of ζ Ursae Majoris, [[α Ursae Majoris]], [[β Ursae Majoris]], [[γ Ursae Majoris]], [[δ Ursae Majoris]], [[ε Ursae Majoris]] and [[η Ursae Majoris]]. Consequently, ζ Ursae Majoris itself is known as {{lang|zh|北斗六}} Běi Dǒu liù, ({{lang-en|the Fifth Star of Northern Dipper}}) and {{lang|zh|開陽}} Kāi Yáng, ({{lang-en|Star of The Opener of Heat}}).<ref name=zh/>
In [[Chinese language|Chinese]], {{lang|zh|北斗}} ({{lang|zh-Latn|Běi Dǒu}}), meaning ''[[Purple Forbidden enclosure|Northern Dipper]]'', refers to an asterism consisting of ζ Ursae Majoris, [[α Ursae Majoris]], [[β Ursae Majoris]], [[γ Ursae Majoris]], [[δ Ursae Majoris]], [[ε Ursae Majoris]] and [[η Ursae Majoris]]. Consequently, ζ Ursae Majoris itself is known as {{lang|zh|北斗六}} Běi Dǒu liù, ({{lang-en|the Fifth Star of Northern Dipper}}) and {{lang|zh|開陽}} Kāi Yáng, ({{lang-en|Star of The Opener of Heat}}).<ref name=zh/>
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<ref name=ubv>{{cite journal|bibcode=1965S&T....30...21I|title=Five-Color Photometry of Bright Stars|journal=Sky and Telescope|volume=30|author1=Iriarte|first1=Braulio|last2=Johnson|first2=Harold L|last3=Mitchell|first3=Richard I|last4=Wisniewski|first4=Wieslaw K|year=1965}}</ref>
<ref name=ubv>{{cite journal|bibcode=1965S&T....30...21I|title=Five-Color Photometry of Bright Stars|journal=Sky and Telescope|volume=30|author1=Iriarte|first1=Braulio|last2=Johnson|first2=Harold L|last3=Mitchell|first3=Richard I|last4=Wisniewski|first4=Wieslaw K|year=1965}}</ref>

<ref name=jaschek>{{cite journal|bibcode=1991A&A...252..229J|title=Anomalous infrared emitters among A-type stars|journal=Astronomy and Astrophysics (ISSN 0004-6361)|volume=252|pages=229|author1=Jaschek|first1=C|last2=Jaschek|first2=M|last3=Egret|first3=D|last4=Andrillat|first4=Y|year=1991}}</ref>

⚫
<ref name=abt>{{cite journal|bibcode=1995ApJS...99..135A|title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars|journal=Astrophysical Journal Supplement v.99|volume=99|pages=135|author1=Abt|first1=Helmut A|last2=Morrell|first2=Nidia I|year=1995|doi=10.1086/192182}}</ref>


<ref name=sb9>{{cite journal|bibcode= 2004A&A...424..727P |title= SB9: The ninth catalogue of spectroscopic binary orbits |journal= Astronomy and Astrophysics |volume= 424 |issue= 2 |pages= 727 |author1= Pourbaix |first1= D |last2= Tokovinin |first2= A. A |last3= Batten |first3= A. H |last4= Fekel |first4= F. C |last5= Hartkopf |first5= W. I |last6= Levato |first6= H |last7= Morrell |first7= N. I |last8= Torres |first8= G |last9= Udry |first9= S |year= 2004 |doi= 10.1051/0004-6361:20041213 }}</ref>
<ref name=sb9>{{cite journal|bibcode= 2004A&A...424..727P |title= SB9: The ninth catalogue of spectroscopic binary orbits |journal= Astronomy and Astrophysics |volume= 424 |issue= 2 |pages= 727 |author1= Pourbaix |first1= D |last2= Tokovinin |first2= A. A |last3= Batten |first3= A. H |last4= Fekel |first4= F. C |last5= Hartkopf |first5= W. I |last6= Levato |first6= H |last7= Morrell |first7= N. I |last8= Torres |first8= G |last9= Udry |first9= S |year= 2004 |doi= 10.1051/0004-6361:20041213 }}</ref>
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<ref name=ref65zigip>{{cite book | title=Astronomy Quiz Book | author=V.Chandran | publisher=Pustak Mahal, 1993 | isbn=978-81-223-0366-7 | url=https://books.google.com/books?id=8iPU8bZQQdsC | quote=''... the seven rishis in the constellation Saptarishi (Ursa Major) ... In Vasishta (Zeta), its tiny companion star is named after Arundhati, the wife of Vasishta ... today known by their Arabic names Dubhe (Kratu), Merak (Pulaha), Phekda (Pulastya), Megrez (Atri), Benetnash (Marichi) and Mizar (Vasishta) ...''| date=1993-01-01 }}</ref>
<ref name=ref65zigip>{{cite book | title=Astronomy Quiz Book | author=V.Chandran | publisher=Pustak Mahal, 1993 | isbn=978-81-223-0366-7 | url=https://books.google.com/books?id=8iPU8bZQQdsC | quote=''... the seven rishis in the constellation Saptarishi (Ursa Major) ... In Vasishta (Zeta), its tiny companion star is named after Arundhati, the wife of Vasishta ... today known by their Arabic names Dubhe (Kratu), Merak (Pulaha), Phekda (Pulastya), Megrez (Atri), Benetnash (Marichi) and Mizar (Vasishta) ...''| date=1993-01-01 }}</ref>

<ref name=ref50haduv>{{cite book | title=Flipside of Hindu Symbolism: Sociological and Scientific Linkages in Hinduism | author=M.K.V. Narayan | publisher=Fultus Corporation, 2007 | isbn=978-1-59682-117-0 | url=https://books.google.com/books?id=ewRfp4qpvt4C | quote=''... At this time, the pundit shows the couple the Arundhati star in the sky to suggest closeness of the married couple. ... the star Vasishta of the Big Dipper constellation (Saptarishi Mandalam) and it is the star system called Mizar ...''| date=2007-04-01 }}</ref>


<ref name=zh>{{cite web|url=http://aeea.nmns.edu.tw/2006/0606/ap060615.html|trans-title=AEEA (Activities of Exhibition and Education in Astronomy)|title=天文教育資訊網|language=zh|accessdate=2018-01-01}}</ref>
<ref name=zh>{{cite web|url=http://aeea.nmns.edu.tw/2006/0606/ap060615.html|trans-title=AEEA (Activities of Exhibition and Education in Astronomy)|title=天文教育資訊網|language=zh|accessdate=2018-01-01}}</ref>
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<ref name=Micmac>{{cite web|url=http://capebretonsmagazine.com/modules/publisher/item.php?itemid=71|title=The Celestial Bear, A Micmac Legend|accessdate=2018-01-01}}</ref>
<ref name=Micmac>{{cite web|url=http://capebretonsmagazine.com/modules/publisher/item.php?itemid=71|title=The Celestial Bear, A Micmac Legend|accessdate=2018-01-01}}</ref>


<ref name=benson>{{cite journal|bibcode=1997AJ....114.1221B|title=Multichannel optical aperture synthesis imaging of zeta1 URSAE majoris with the Navy prototype optical interferometer|journal=Astronomical Journal |volume=114|pages=1221|author1=Benson|first1=J. A|last2=Hutter|first2=D. J|last3=Elias|first3=N. M|last4=Bowers|first4=P. F|last5=Johnston|first5=K. J|last6=Hajian|first6=A. R|last7=Armstrong|first7=J. T|last8=Mozurkewich|first8=D|last9=Pauls|first9=T. A|last10=Rickard|first10=L. J|last11=Hummel|first11=C. A|last12=White|first12=N. M|last13=Black|first13=D|last14=Denison|first14=C. S|year=1997|doi=10.1086/118554}}</ref>
<ref name=benson>{{cite journal|bibcode=1997AJ....114.1221B}}</ref>

<ref name="Marett-Crosby2013">{{cite book|author=Michael Marett-Crosby|title=Twenty-Five Astronomical Observations That Changed the World: And How To Make Them Yourself|url=https://books.google.com/books?id=0KRSphlvsqgC&pg=PA32|date=28 June 2013|publisher=Springer Science & Business Media|isbn=978-1-4614-6800-4|pages=32–}}</ref>

<ref name=dick>{{cite book|author=Steven J. Dick|title=Discovery and Classification in Astronomy: Controversy and Consensus|url=https://books.google.com/books?id=IT8oAAAAQBAJ&pg=PA117|date=9 September 2013|publisher=Cambridge University Press|isbn=978-1-107-03361-0|pages=117–}}</ref>

<ref name=eggletonubv>{{cite journal|bibcode=1986EgUBV........0M|title=Compilation of Eggen's UBV data, transformed to UBV (unpublished)|journal=Catalogue of Eggen's UBV data|author1=Mermilliod|first1=J.-C|year=1986}}</ref>

<ref name=allen>{{cite book|author=Richard H. Allen|title=Star Names: Their Lore and Meaning|url=https://books.google.com/books?id=vWDsybJzz7IC|date=28 February 2013|publisher=Courier Corporation|isbn=978-0-486-13766-7}}</ref>

<ref name=consolmagno>{{cite book|author1=Guy Consolmagno|author2=Dan M. Davis|title=Turn Left at Orion: A Hundred Night Sky Objects to See in a Small Telescope - and How to Find Them|url=https://books.google.com/books?id=PexKTfPy3voC&pg=PA83|date=19 October 2000|publisher=Cambridge University Press|isbn=978-1-139-45750-7|pages=83–}}</ref>

<ref name=jones>{{cite journal|bibcode=2015ApJ...813...58J|arxiv=1508.05643|title=The Ages of A-Stars. I. Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group|journal=The Astrophysical Journal|volume=813|pages=58|author1=Jones|first1=Jeremy|last2=White|first2=R. J|last3=Boyajian|first3=T|last4=Schaefer|first4=G|last5=Baines|first5=E|last6=Ireland|first6=M|last7=Patience|first7=J|last8=Ten Brummelaar|first8=T|last9=McAlister|first9=H|last10=Ridgway|first10=S. T|last11=Sturmann|first11=J|last12=Sturmann|first12=L|last13=Turner|first13=N|last14=Farrington|first14=C|last15=Goldfinger|first15=P. J|year=2015|doi=10.1088/0004-637X/813/1/58}}</ref>

<ref name=burnham>{{cite book|author=Robert Burnham|title=Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System|url=https://books.google.com/books?id=tBQoCSRdLAAC|year=1978|publisher=Courier Corporation|isbn=978-0-486-23673-5}}</ref>

<ref name=behr>{{cite journal|bibcode=2011AJ....142....6B|arxiv=1104.1447|title=Stellar Astrophysics with a Dispersed Fourier Transform Spectrograph. II. Orbits of Double-lined Spectroscopic Binaries|journal=The Astronomical Journal|volume=142|pages=6|author1=Behr|first1=Bradford B|last2=Cenko|first2=Andrew T|last3=Hajian|first3=Arsen R|last4=McMillan|first4=Robert S|last5=Murison|first5=Marc|last6=Meade|first6=Jeff|last7=Hindsley|first7=Robert|year=2011|doi=10.1088/0004-6256/142/1/6}}</ref>

<ref name=thureau>{{cite journal|bibcode=2014MNRAS.445.2558T|title=An unbiased study of debris discs around A-type stars with Herschel|journal=Monthly Notices of the Royal Astronomical Society|volume=445|issue=3|pages=2558|author1=Thureau|first1=N. D|last2=Greaves|first2=J. S|last3=Matthews|first3=B. C|last4=Kennedy|first4=G|last5=Phillips|first5=N|last6=Booth|first6=M|last7=Duchêne|first7=G|last8=Horner|first8=J|last9=Rodriguez|first9=D. R|last10=Sibthorpe|first10=B|last11=Wyatt|first11=M. C|year=2014|doi=10.1093/mnras/stu1864}}</ref>

<ref name=gray>{{cite journal|bibcode=1987ApJS...65..581G|title=The early a type stars - Refined MK classification, confrontation with Stroemgren photometry, and the effects of rotation|journal=Astrophysical Journal Supplement Series|volume=65|pages=581|author1=Gray|first1=R. O|last2=Garrison|first2=R. F|year=1987|doi=10.1086/191237}}</ref>

⚫
<ref name=abt>{{cite journal|bibcode=1984ApJ...276..266A|title=The nature of the visual companions of AP and AM stars|journal=Astrophysical Journal|volume=276|pages=266|author1=Abt|first1=H. A|last2=Cardona|first2=O|year=1984|doi=10.1086/161610}}</ref>


}}
}}
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{{Stars of Ursa Major}}
{{Stars of Ursa Major}}
{{Sky|13|23|55.5|+|54|55|31|78}}
{{Sky|13|23|55.5|+|54|55|31}}

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[[Category:A-type main-sequence stars]]
[[Category:A-type main-sequence stars]]
[[Category:Bayer objects|Ursae Majoris, Zeta]]
[[Category:Am stars]]
[[Category:Big Dipper]]
[[Category:Ap star]]
[[Category:Flamsteed objects|Ursae Majoris, 79]]
[[Category:Spectroscopic binaries]]
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[[Category:A-type subgiants]]
[[Category:Multiple star systems|4]]
[[Category:Multiple star systems|4]]
[[Category:Ursa Major Moving Group]]
<!-- Catalogues -->
[[Category:Stars with proper names]]
[[Category:Stars with proper names]]
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[[Category:Bayer objects|Ursae Majoris, Zeta]]
[[Category:Big Dipper]]
[[Category:Ursa Major (constellation)]]
[[Category:Ursa Major (constellation)]]
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[[Category:HR objects|5054]]
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[[Category:Hipparcos objects|065378]]
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[[Category:Henry Draper Catalogue objects|116656]]
[[Category:Durchmusterung objects|BD+55 1598]]
[[Category:Durchmusterung objects|BD+55 1598]]
[[Category:Am stars]]
[[Category:Flamsteed objects|Ursae Majoris, 79]]
[[Category:Ap star]]
[[Category:Henry Draper Catalogue objects|116656 7]]
[[Category:Spectroscopic binaries]]
[[Category:Hipparcos objects|065378]]
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[[Category:HR objects|5054 5]]

Revision as of 11:05, 22 April 2018

Mizar
Location of Mizar (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ursa Major
Mizar
Right ascension 13h 23m 55.54048s[1]
Declination +54° 55′ 31.2671″[1]
Apparent magnitude (V) 2.04[2]
ζ1 UMa
Right ascension 13h 23m 55.543s[3]
Declination +54° 55′ 31.30″[3]
Apparent magnitude (V) 2.23[3]
ζ2 UMa
Right ascension 13h 23m 56.330s[3]
Declination +54° 55′ 18.56″[3]
Apparent magnitude (V) 3.88[3]
Characteristics
ζ1 UMa
Spectral type A2Vp/A2Vp[4]
U−B color index −0.01[5]
B−V color index +0.02[5]
ζ2 UMa
Spectral type kA1h(eA)mA7IV-V[6]
U−B color index +0.09[5]
B−V color index +0.13[5]
Astrometry
Radial velocity (Rv)−6.31[7] km/s
Proper motion (μ) RA: 119.01[1] mas/yr
Dec.: −25.97[1] mas/yr
Parallax (π)39.36 ± 0.30 mas[8]
Distance82.9 ± 0.6 ly
(25.4 ± 0.2 pc)
Absolute magnitude (MV)+0.32/+1.96[9]
Orbit
PrimaryMizar Aa
CompanionMizar Ab
Period (P)20.5386 days[10]
Semi-major axis (a)9.83±0.03[11]″
Eccentricity (e)0.5415±0.0016[10]
Inclination (i)60.5±0.3[10]°
Longitude of the node (Ω)106.0±0.4[11]°
Periastron epoch (T)RJD 54536.9904[10]
Argument of periastron (ω)
(secondary)		105.27±0.23[10]°
Semi-amplitude (K1)
(primary)		66.478±0.153[10] km/s
Semi-amplitude (K2)
(secondary)		66.019±0.177[10] km/s
Orbit
PrimaryMizar Ba
CompanionMizar Bb
Period (P)175.55[12]
Semi-major axis (a)29.849 mas
Eccentricity (e)0.46[12]
Details
Mizar Aa
Mass2.2224±0.0221[10] M☉
Radius2.4 ± 0.1[11] R☉
Luminosity33.3 ± 2.1[11] L☉
Temperature9,000 ± 200[11] K
Age370[13] Myr
Mizar Ab
Mass2.2381±0.0219[10] M☉
Radius2.4 ± 0.1[11] R☉
Luminosity33.3 ± 2.1[11] L☉
Temperature9,000 ± 200[11] K
ζ2 UMa
Surface gravity (log g)4.40[14] cgs
Temperature8,425[14] K
Rotational velocity (v sin i)61[14] km/s
Other designations
ζ Ursae Majoris, ζ UMa, Zeta UMa, 79 Ursae Majoris, BD+55 1598, CCDM J13240+5456, HIP 65378, WDS J13239+5456
ζ1 UMa: GC 18133, HD 116656, HR 5054, PPM 34007, SAO 28737
ζ2 UMa: GC 18134, HD 116657, HR 5055, SAO 28738
Database references
SIMBADMizar
ζ1 UMa
ζ2 UMa

Mizar is a 2nd magnitude star in the handle of the Big Dipper asterism in the constellation of Ursa Major. It has the Bayer designation ζ Ursae Majoris (Latinised as Zeta Ursae Majoris). It forms a well-known naked eye double star with the fainter star Alcor, and is itself a quadruple star system. The whole system lies about 83 light-years away from the Sun, as measured by the Hipparcos astrometry satellite, and is part of the Ursa Major Moving Group.

Nomenclature

ζ Ursae Majoris (Latinised to Zeta Ursae Majoris and abbreviated to ζ UMa or Zeta UMa) is Mizar's Bayer designation. It also has the Flamsteed designation 79 Ursae Majoris.

The traditional name Mizar derives from the Arabic المئزر miʼzar meaning 'apron; wrapper, covering, cover'.[15] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[16] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016[17] included a table of the first two batches of names approved by the WGSN; which included Mizar for ζ UMa. According to IAU rules, the name Mizar strictly only applies to component Aa,[18] although it is traditionally and popularly used for all four stars making up the single naked-eye star.[19][20]

Stellar system

The Big Dipper's bowl and part of the handle photographed from the International Space Station. Mizar and Alcor are at the upper right.

Mizar is a visual double with a separation of 14.4 arcseconds, each of which is a spectroscopic binary. Its combined apparent magnitude is 2.04. The two visible stars are referred to as ζ1 and ζ2 Ursae Majoris, or Mizar A and B. The spectroscopic components are generally referred to as Mizar Aa, Ab, Ba, and Bb. The stars all share a single Hipparcos designation of HIP 65378, but separate Bright Star Catalogue and Henry Draper Catalogue entries. Mizar, together with Alcor and many of the other bright stars in Ursa Major, is a member of the Ursa Major Moving Group.[21]

An easily split visual target, Mizar was the first telescopic binary discovered, most probably by Benedetto Castelli who in 1617 asked Galileo Galilei to observe it. Galileo then produced a detailed record of the double star.[22] Later, around 1650, Riccioli wrote of Mizar appearing as a double.[23] The secondary star (Mizar B) comes within 380 AU of the primary (Mizar A) and the two take thousands of years to revolve around each other.[24]

Mizar A was the first spectroscopic binary to be discovered, as part of Antonia Maury's spectral classification work, and an orbit was published in 1890. Some spectroscopic binaries cannot be visually resolved and are discovered by studying the spectral lines of the suspect system over a long period of time. The two components of Mizar A are both about 35 times as bright as the Sun, and revolve around each other in about 20 days 12 hours and 55 minutes. In 1908, Mizar B was also found to be a spectroscopic binary, its components completing an orbital period every six months.[8] In 1996, 107 years after their discovery, the components of the Mizar A binary system were imaged in extremely high resolution using the Navy Prototype Optical Interferometer.[25]

ζ1 Ursae Majoris

Radial velocity curves for the two almost identical components

The two components of ζ1 Ursae Majoris (Mizar Aa and Ab) are observed to be identical, with the exception of slightly different radial velocity variations which indicate very slightly different masses.

The spectral lines of the two stars can be observed separately and both are given a spectral type of A2Vp. They are Ap stars, chemically peculiar due to stratification of some heavy elements in the photosphere of slowly-rotating hot stars. In this case, they show elevated abundances of strontium and silicon.[26]

With the assumption of identical physical properties for the two stars, they both have temperatures of 9,000 K, radii of 2.4 R☉, and bolometric luminosities of 33.3 L☉.[11] They are thought to be around 370 million years old.[13]

ζ2 Ursae Majoris

ζ2 Ursae Majoris is a single-lined spectroscopic binary, and the visible spectrum is of an Am star, named for their unusually strong lines of some metals. The spectral type of kA1h(eA)mA7IV-V is in a form used for metallic-lined stars: the type is A1 based on the calcium K lines, early A based on the hydrogen lines, and A7 based on lines of other metals. The luminosity class is ranked between main sequence and subgiant.

Other names

Mizar is known as Vashistha one of the Saptarishi, in traditional Indian astronomy.[27]

Al-Sahja was the rhythmical form of the usual Suha. It appears as الخوّار al-Khawwar, 'the Faint One', in an interesting list of Arabic star names, published in Popular Astronomy, January 1895, by Professor Robert H. West, of the Syrian Protestant College at Beirut.[citation needed]

Chinese Taoism personifies ζ Ursae Majoris as the Lu star.[citation needed]

In Chinese, 北斗 (Běi Dǒu), meaning Northern Dipper, refers to an asterism consisting of ζ Ursae Majoris, α Ursae Majoris, β Ursae Majoris, γ Ursae Majoris, δ Ursae Majoris, ε Ursae Majoris and η Ursae Majoris. Consequently, ζ Ursae Majoris itself is known as 北斗六 Běi Dǒu liù, (English: the Fifth Star of Northern Dipper) and 開陽 Kāi Yáng, (English: Star of The Opener of Heat).[28]

Mizar is Chickadee and Alcor is his cooking pot in the Mi'kmaq myth of the great bear and the seven hunters.[29]

Military namesakes

See also

References

  1. ^ a b c d van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. ^ Mermilliod, J.-C (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV data. Bibcode:1986EgUBV........0M.
  3. ^ a b c d e f Fabricius, C; Høg, E; Makarov, V. V; Mason, B. D; Wycoff, G. L; Urban, S. E (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384: 180. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822.
  4. ^ Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  5. ^ a b c d Iriarte, Braulio; Johnson, Harold L; Mitchell, Richard I; Wisniewski, Wieslaw K (1965). "Five-Color Photometry of Bright Stars". Sky and Telescope. 30. Bibcode:1965S&T....30...21I.
  6. ^ Gray, R. O; Garrison, R. F (1987). "The early a type stars - Refined MK classification, confrontation with Stroemgren photometry, and the effects of rotation". Astrophysical Journal Supplement Series. 65: 581. Bibcode:1987ApJS...65..581G. doi:10.1086/191237.
  7. ^ Pourbaix, D; Tokovinin, A. A; Batten, A. H; Fekel, F. C; Hartkopf, W. I; Levato, H; Morrell, N. I; Torres, G; Udry, S (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213.
  8. ^ a b Mamajek, Eric E.; Kenworthy, Matthew A.; Hinz, Philip M.; Meyer, Michael R. (2010). "Discovery of a Faint Companion to Alcor Using MMT/AO 5 μm Imaging". The Astronomical Journal. 139 (3): 919–925. arXiv:0911.5028. Bibcode:2010AJ....139..919M. doi:10.1088/0004-6256/139/3/919.
  9. ^ King, Jeremy R; Villarreal, Adam R; Soderblom, David R; Gulliver, Austin F; Adelman, Saul J (2003). "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group". The Astronomical Journal. 125 (4): 1980. Bibcode:2003AJ....125.1980K. doi:10.1086/368241.
  10. ^ a b c d e f g h i Behr, Bradford B; Cenko, Andrew T; Hajian, Arsen R; McMillan, Robert S; Murison, Marc; Meade, Jeff; Hindsley, Robert (2011). "Stellar Astrophysics with a Dispersed Fourier Transform Spectrograph. II. Orbits of Double-lined Spectroscopic Binaries". The Astronomical Journal. 142: 6. arXiv:1104.1447. Bibcode:2011AJ....142....6B. doi:10.1088/0004-6256/142/1/6.
  11. ^ a b c d e f g h i Hummel, C. A.; Mozurkewich, D.; Armstrong, J. T.; Hajian, Arsen R.; Elias Ii, N. M.; Hutter, D. J. (1998). "Navy Prototype Optical Interferometer Observations of the Double Stars Mizar a and Matar". The Astronomical Journal. 116 (5): 2536. Bibcode:1998AJ....116.2536H. doi:10.1086/300602.
  12. ^ a b Iliev, I. Kh; Budaj, J; Zverko, J; Barzova, I. S; Ziznovsky, J (1998). "Lithium and metal abundances in long period AM binaries". Astronomy and Astrophysics Supplement. 128 (3): 497. Bibcode:1998A&AS..128..497I. doi:10.1051/aas:1998160.
  13. ^ a b Thureau, N. D; Greaves, J. S; Matthews, B. C; Kennedy, G; Phillips, N; Booth, M; Duchêne, G; Horner, J; Rodriguez, D. R; Sibthorpe, B; Wyatt, M. C (2014). "An unbiased study of debris discs around A-type stars with Herschel". Monthly Notices of the Royal Astronomical Society. 445 (3): 2558. Bibcode:2014MNRAS.445.2558T. doi:10.1093/mnras/stu1864.
  14. ^ a b c Monier, R (2005). "Abundances of a sample of a and F-type dwarf members of the Ursa Major Group". Astronomy and Astrophysics. 442 (2): 563. Bibcode:2005A&A...442..563M. doi:10.1051/0004-6361:20053222.
  15. ^ Wehr, Hans (1994). A Dictionary of Modern Written Arabic (Arabic-English) (4 ed.). Urbana, Illinois: Spoken Language Services. p. 17. ISBN 0879500034.
  16. ^ "IAU Working Group on Star Names (WGSN)". Retrieved 22 May 2016.
  17. ^ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Retrieved 28 July 2016.
  18. ^ "IAU Catalog of Star Names". Retrieved 28 July 2016.
  19. ^ Richard H. Allen (28 February 2013). Star Names: Their Lore and Meaning. Courier Corporation. ISBN 978-0-486-13766-7.
  20. ^ Guy Consolmagno; Dan M. Davis (19 October 2000). Turn Left at Orion: A Hundred Night Sky Objects to See in a Small Telescope - and How to Find Them. Cambridge University Press. pp. 83–. ISBN 978-1-139-45750-7.
  21. ^ Jones, Jeremy; White, R. J; Boyajian, T; Schaefer, G; Baines, E; Ireland, M; Patience, J; Ten Brummelaar, T; McAlister, H; Ridgway, S. T; Sturmann, J; Sturmann, L; Turner, N; Farrington, C; Goldfinger, P. J (2015). "The Ages of A-Stars. I. Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group". The Astrophysical Journal. 813: 58. arXiv:1508.05643. Bibcode:2015ApJ...813...58J. doi:10.1088/0004-637X/813/1/58.
  22. ^ Michael Marett-Crosby (28 June 2013). Twenty-Five Astronomical Observations That Changed the World: And How To Make Them Yourself. Springer Science & Business Media. pp. 32–. ISBN 978-1-4614-6800-4.
  23. ^ Steven J. Dick (9 September 2013). Discovery and Classification in Astronomy: Controversy and Consensus. Cambridge University Press. pp. 117–. ISBN 978-1-107-03361-0.
  24. ^ Robert Burnham (1978). Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System. Courier Corporation. ISBN 978-0-486-23673-5.
  25. ^ Benson, J. A; Hutter, D. J; Elias, N. M; Bowers, P. F; Johnston, K. J; Hajian, A. R; Armstrong, J. T; Mozurkewich, D; Pauls, T. A; Rickard, L. J; Hummel, C. A; White, N. M; Black, D; Denison, C. S (1997). "Multichannel optical aperture synthesis imaging of zeta1 URSAE majoris with the Navy prototype optical interferometer". Astronomical Journal. 114: 1221. Bibcode:1997AJ....114.1221B. doi:10.1086/118554.
  26. ^ Abt, H. A; Cardona, O (1984). "The nature of the visual companions of AP and AM stars". Astrophysical Journal. 276: 266. Bibcode:1984ApJ...276..266A. doi:10.1086/161610.
  27. ^ V.Chandran (1993-01-01). Astronomy Quiz Book. Pustak Mahal, 1993. ISBN 978-81-223-0366-7. ... the seven rishis in the constellation Saptarishi (Ursa Major) ... In Vasishta (Zeta), its tiny companion star is named after Arundhati, the wife of Vasishta ... today known by their Arabic names Dubhe (Kratu), Merak (Pulaha), Phekda (Pulastya), Megrez (Atri), Benetnash (Marichi) and Mizar (Vasishta) ...
  28. ^ "天文教育資訊網" [AEEA (Activities of Exhibition and Education in Astronomy)] (in Chinese). Retrieved 2018-01-01.
  29. ^ "The Celestial Bear, A Micmac Legend". Retrieved 2018-01-01.

External links

source: https://en.wikipedia.org/w/index.php?title=Zeta_Ursae_Majoris&action=historysubmit&type=revision&diff=837687939&oldid=818136498

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