View source for Beta Tauri

{{Short description|Star in the constellation Taurus}}
{{redirect-multi|3|Elnath|Alnath|Nath (star)|other topics|El Nath (disambiguation)|and|Nath (disambiguation)}}
{{Starbox begin
 | name=β Tauri
}}
{{Starbox image
 | image=
{{Location mark
|image=Taurus constellation map.svg|alt=|float=center|width=240
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=β Tauri
|x=190|y=196
}}
|caption=Location of β Tauri in Taurus (circled)
}}
{{Starbox observe
 |pronounce = {{IPAc-en|E|l|'|n|æ|θ}}<ref>{{OED|Alnath}}</ref> or {{IPAc-en|'|E|l|n|æ|θ}}<ref name=Kunitzsch/>
 |epoch=J2000
 |ra={{RA|05|26|17.51312}}<ref name=hipparcos/>
 |dec={{DEC|+28|36|26.8262}}<ref name=hipparcos/>
 |appmag_v=1.65<ref name=ducati/>
 |constell=[[Taurus (constellation)|Taurus]]
}}
{{Starbox character
  |class=B7III<ref name=garrison/>
  |b-v=−0.13<ref name=ducati/>
  |u-b=−0.49<ref name=ducati/>
  |variable=
}}
{{Starbox astrometry
  |radial_v=9.2<ref name=rv/>
  |prop_mo_ra=+22.76<ref name=hipparcos/>
  |prop_mo_dec=−173.58<ref name=hipparcos/>
  |parallax=24.36
  |p_error=0.34
  |parallax_footnote=<ref name=hipparcos/>
  |absmag_v=−1.42<ref name=Anderson2012/>
}}
{{Starbox detail
 | mass=5.0{{±|0.1}}<ref name=apj736_2_89/>
 | radius={{val|4.82|0.34}}<ref name=gordon2019/>{{snd}}{{val|5.47|0.24}}<ref name=baines/>
 | luminosity={{val|564|20}}<ref name=baines/>
 | temperature=13,600{{±|100}}<ref name=gordon2019/>
 | metal_fe=+0.2<ref name=baines/>
 | rotational_velocity=59<ref name=hgmn/>
 | gravity=3.63<ref name=baines/>
 | age_myr=100{{±|10}}<ref name=apj736_2_89/>
}}
{{Starbox catalog
 |names={{odlist | name=Elnath | name2=El Nath | name3=Alnath | B=Gamma Aurigae | F=112&nbsp;Tauri | BD=+28°795 | FK5=202 | HD=35497 | HIP=25428 | HR=1791 | SAO=77168 | WDS= | CCDM=05263+2836 | GC=6681 }}
}}
{{Starbox reference
 | Simbad=HD+35497
}}
{{Starbox end}}

'''Beta Tauri''' is the second-brightest [[star]] in the [[constellation]] of [[Taurus (constellation)|Taurus]]. It has the official name '''Elnath'''; ''Beta Tauri'' is the current [[Bayer designation]], which is [[Latinisation of names|Latinised]] from '''β Tauri''' and abbreviated '''Beta Tau''' or '''β Tau'''. The original designation of Gamma Aurigae is now rarely used. It is a [[chemically peculiar star|chemically peculiar]] B7 [[giant star]], 134 [[light year]]s away from the Sun with an [[apparent magnitude]] of 1.65.

==Nomenclature==
This star has two [[Bayer designation]]s: β Tauri (Latinised to Beta Tauri) and γ Aurigae (Latinised to Gamma Aurigae). [[Ptolemy]] considered the star to be shared by [[Auriga (constellation)|Auriga]], and [[Johann Bayer]] assigned it a designation in both constellations. When the modern constellation boundaries were fixed in 1930, the designation γ Aurigae largely dropped from use.<ref name=ridpath/>

The traditional name ''Elnath'', variously ''El Nath'' or ''Alnath'', comes from the Arabic word '''النطح''' ''an-naţħ'', meaning "the butting" (''i.e.'' the bull's horns). As in many other Arabic star names, the article '''ال''' is transliterated literally as ''el'', yet overwhelmingly in Arabic pronunciation it is assimilated to the ''n'', meaning it is omitted. 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 ''Elnath'' for this star.<ref name="IAU-CSN"/>

In [[Chinese astronomy|Chinese]], {{lang|zh|五車}} ({{lang|zh-Latn|Wǔ Chē}}), meaning ''[[Five Chariots]]'', refers to an asterism consisting of β Tauri, [[Iota Aurigae|ι Aurigae]], [[Capella]], [[Beta Aurigae|β Aurigae]] and [[Theta Aurigae|θ Aurigae]].<ref>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}.</ref> Consequently, the [[Chinese star names|Chinese name]] for β Tauri itself is {{lang|zh|五車五}} ({{lang|zh-Latn|Wǔ Chē Wǔ}}; {{langx|en|Fifth of the Five Chariots}}.)<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_e_g.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20110130063007/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_e_g.htm |date=2011-01-30 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>

== Physical properties ==
The [[absolute magnitude]] of Beta Tauri is −1.34, similar to another star in Taurus, [[Maia (star)|Maia]] in the [[Pleiades]] [[Open cluster|star cluster]]. Like Maia, β Tauri is a [[B-type giant|B-class]] [[Giant star|giant]] with a luminosity 700 times solar ({{solar luminosity}}).<ref name="kaler" /> It has evolved to become a giant star, larger and cooler than when it was on the [[main sequence]].<ref name=knyazeva/>
However, being approximately 130 [[light-year]]s distant compared to Maia's estimated 360 light-years, β Tauri ranks as the second-brightest star in the constellation.

It is a [[mercury-manganese star]], a type of non-magnetic chemically peculiar star with unusually large signatures of some heavy elements in its [[stellar spectrum|spectrum]].<ref name=hgmn/> Relative to the [[Sun]], β Tauri is notable for a high abundance of [[manganese]], but little [[calcium]] and [[magnesium]].<ref name="kaler" /><ref name="aj41" /> However, the lack of strong [[mercury (element)|mercury]] signatures, together with notably high levels of [[silicon]] and [[chromium]], have led some authors to give other classifications, including as a "SrCrEu star" or even an [[Ap star]].<ref name=chen/><ref name=bychkov/>  Its [[limb darkening|limb-darkened]] angular diameter has been measured at {{val|1.090|0.076|ul=mas}}.  At a distance of {{val|41.1|u=pc}}, this corresponds to a linear radius of {{val|4.82|0.34|u=solar radius}}.<ref name=gordon2019/>

At the southern edge of the narrow plane of the [[Milky Way|Milky Way Galaxy]] a few degrees west of the [[galactic anticenter]], β Tauri figures (appears) as a foreground object south of many [[nebula]]e and [[star cluster]]s such as [[Messier 36|M36]], [[Messier 37|M37]], and [[Messier 38|M38]].<ref name="ApopPik"/> It is 5.39 degrees north of the [[ecliptic]], still few enough to be occultable by the [[Moon]]. Such occultations occur when the Moon's [[ascending node]] is near the [[Equinox (celestial coordinates)|March equinox]], as in 2007. Most are visible only in the [[Southern Hemisphere]], because the star is at the northern edge of the lunar occultation zone &ndash; but rarely as far north as southern [[California]].<ref name=abrams/>

== Companions ==
A faint star is, angularly from our viewpoint, close enough for astronomers to consider, and guides to mention, the pair as a [[double star]]. This visual companion, BD+28°795B, has a [[position angle]] of 239 degrees and is separated from the main star by 33.4 [[Minute and second of arc|arcseconds]] (″).<ref name=VizieR/><ref name="Alcyone"/>  Six angularly closer, even fainter stars have been found in a search for brown dwarf and planetary companions{{snd}}all considered background objects.<ref name=janson/>

A very close companion was reported from [[lunar occultation]] measurements at a distance of {{val|0.1|ul="}}, but not confirmed by other observers.  [[Radial velocity]] measurements indicate that Beta Tauri is a single-lined [[spectroscopic binary]], but there is no published information about the companion or orbit.<ref name=adelman2006/><ref name=gordon2019/>

== References ==
{{Reflist|refs=

<ref name=adelman2006>{{cite journal |doi=10.1051/0004-6361:20053581 |title=Elemental abundance analyses with DAO spectrograms |year=2006 |last1=Adelman |first1=S. J. |last2=Caliskan |first2=H. |last3=Gulliver |first3=A. F. |last4=Teker |first4=A. |journal=Astronomy & Astrophysics |volume=447 |issue=2 |pages=685–690 |doi-access=free |bibcode=2006A&A...447..685A }}</ref>

<ref name=janson>{{cite journal|bibcode=2011ApJ...736...89J|arxiv=1105.2577|title=High-contrast Imaging Search for Planets and Brown Dwarfs around the Most Massive Stars in the Solar Neighborhood|journal=[[The Astrophysical Journal]]|volume=736|issue=2|pages=89|last1=Janson|first1=Markus|last2=Bonavita|first2=Mariangela|last3=Klahr|first3=Hubert|last4=Lafrenière|first4=David|last5=Jayawardhana|first5=Ray|last6=Zinnecker|first6=Hans|year=2011|doi=10.1088/0004-637X/736/2/89|s2cid=119217803}}</ref>

<ref name=baines>{{cite journal |bibcode=2021AJ....162..198B |title=Angular Diameters and Fundamental Parameters of Forty-four Stars from the Navy Precision Optical Interferometer |last1=Baines |first1=Ellyn K. |last2=Thomas Armstrong |first2=J. |last3=Clark |first3=James H. |last4=Gorney |first4=Jim |last5=Hutter |first5=Donald J. |last6=Jorgensen |first6=Anders M. |last7=Kyte |first7=Casey |last8=Mozurkewich |first8=David |last9=Nisley |first9=Ishara |last10=Sanborn |first10=Jason |last11=Schmitt |first11=Henrique R. |last12=Van Belle |first12=Gerard T. |journal=The Astronomical Journal |date=2021 |volume=162 |issue=5 |page=198 |doi=10.3847/1538-3881/ac2431 |doi-access=free |arxiv=2211.09030 }}</ref>

<ref name=abrams>{{cite web|url=http://www.pa.msu.edu/abrams/SWD/2006/SWD_0609-g.html|publisher=Abrams Planetarium|title=Skywatcher's Diary|url-status=dead|archive-url=https://web.archive.org/web/20070830182148/http://www.pa.msu.edu/abrams/SWD/2006/SWD_0609-g.html|archive-date=August 30, 2007}}</ref>

<ref name="Alcyone">{{cite web |url=http://www.alcyone.de/SIT/mainstars/SIT000764.htm  | title=Al Nath | publisher=Alcyone Bright Star Catalogue | access-date=2010-03-07 }}</ref>

<ref name=VizieR>{{cite web |title=CCDM (Catalog of Components of Double & Multiple stars (Dommanget+ 2002) |work=[[VizieR]] |publisher=[[Centre de Données astronomiques de Strasbourg]] |url=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?CCDM%20J05263%2b2836B  |access-date=2010-03-07}}</ref>

<ref name="kaler">{{cite web | title=ELNATH (Beta Tauri) | publisher=[[University of Illinois]] | first1=James B. | last1=Kaler | url=http://stars.astro.illinois.edu/sow/elnath.html | access-date=2010-03-07 }}</ref>

<ref name="aj41">{{cite journal  | last1=Heacox | first1=W. D. | title=Chemical abundances in Hg-Mn stars | journal=[[Astrophysical Journal Supplement Series]] | date=1979  | volume=41 | page=675 | bibcode=1979ApJS...41..675H | doi=10.1086/190637 }}</ref>

<ref name=apj736_2_89>{{cite journal | display-authors=1 | last1=Janson | first1=Markus | last2=Bonavita | first2=Mariangela | last3=Klahr | first3=Hubert | last4=Lafrenière | first4=David | last5=Jayawardhana | first5=Ray | last6=Zinnecker | first6=Hans | title=High-contrast Imaging Search for Planets and Brown Dwarfs around the Most Massive Stars in the Solar Neighborhood | journal=[[The Astrophysical Journal]] | volume=736 | issue=2 | page=89 |date=August 2011 | doi=10.1088/0004-637X/736/2/89 | bibcode=2011ApJ...736...89J |arxiv = 1105.2577 | s2cid=119217803 }}</ref>

<ref name=Anderson2012>{{cite journal
 | title=XHIP: An extended hipparcos compilation
 | last1=Anderson | first1=E. | last2=Francis | first2=Ch.
 | journal=[[Astronomy Letters]]
 | volume=38 | issue=5 | pages=331 | year=2012
 | bibcode=2012AstL...38..331A | doi=10.1134/S1063773712050015
 | arxiv=1108.4971 | s2cid=119257644 }}</ref>

<ref name=hipparcos>{{cite journal | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | title=Validation of the new Hipparcos reduction | journal=[[Astronomy and Astrophysics]] | volume=474 | issue=2 | pages=653–664 | year=2007 | last1=Van Leeuwen | first1=F. | s2cid=18759600 }} [http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HIP%2025428 Vizier catalog entry]</ref>

<ref name=rv>{{cite journal|bibcode= 1967IAUS...30...57E |title= The Revision of the General Catalogue of Radial Velocities |journal= Determination of Radial Velocities and Their Applications |volume= 30 |pages= 57 |last1= Evans |first1= D. S |year= 1967 }}</ref>

<ref name=garrison>{{cite journal|bibcode=1994AJ....107.1556G|title=The late B-type stars: Refined MK classification, confrontation with stromgren photometry, and the effects of rotation|journal=[[The Astronomical Journal]]|volume=107|pages=1556|last1=Garrison|first1=R. F|last2=Gray|first2=R. O|year=1994|doi=10.1086/116967}}</ref>

<ref name=hgmn>{{cite journal|bibcode=2016MNRAS.460.1912G|title=Statistical analysis from recent abundance determinations in HgMn stars|journal=[[Monthly Notices of the Royal Astronomical Society]]|volume=460|issue=2|pages=1912|last1=Ghazaryan|first1=S|last2=Alecian|first2=G|year=2016|doi=10.1093/mnras/stw911|doi-access=free}}</ref>

<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="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>

<ref name=ridpath>{{cite web|url=http://www.ianridpath.com/startales/bayer.htm|title=Bayer's Uranometria and Bayer letters|author=Ian Ridpath|author-link=Ian Ridpath|access-date=2017-11-27}}</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="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="ApopPik">{{Cite APOD | title=Deep Auriga | date=5 March 2010  | access-date=2010-03-07 }}</ref>

<ref name=knyazeva>{{cite journal|bibcode=2000ARep...44..548K|title=The Normal Energy Distributions in Stellar Spectra: Giants and Supergiants|journal=[[Astronomy Reports]]|volume=44|issue=8|pages=548|last1=Knyazeva|first1=L. N|last2=Kharitonov|first2=A. V|year=2000|doi=10.1134/1.1306355|s2cid=120800469}}</ref>

<ref name=chen>{{cite journal|bibcode=2017AJ....153..218C|title=A New Photometric Study of Ap and Am Stars in the Infrared|journal=[[The Astronomical Journal]]|volume=153|issue=5|pages=218|last1=Chen|first1=P. S|last2=Liu|first2=J. Y|last3=Shan|first3=H. G|year=2017|doi=10.3847/1538-3881/aa679a|doi-access=free}}</ref>

<ref name=bychkov>{{cite journal|bibcode=2009MNRAS.394.1338B|title=Catalogue of averaged stellar effective magnetic fields - II. Re-discussion of chemically peculiar a and B stars|journal=[[Monthly Notices of the Royal Astronomical Society]]|volume=394|issue=3|pages=1338|last1=Bychkov|first1=V. D|last2=Bychkova|first2=L. V|last3=Madej|first3=J|year=2009|doi=10.1111/j.1365-2966.2008.14227.x|s2cid=120268049 |doi-access=free}}</ref>

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

<ref name=gordon2019>{{cite journal |doi=10.3847/1538-4357/ab04b2  |title=Angular Sizes, Radii, and Effective Temperatures of B-type Stars from Optical Interferometry with the CHARA Array |year=2019 |last1=Gordon |first1=Kathryn D. |last2=Gies |first2=Douglas R. |last3=Schaefer |first3=Gail H. |last4=Huber |first4=Daniel |last5=Ireland |first5=Michael |journal=The Astrophysical Journal |volume=873 |issue=1 |page=91 |bibcode=2019ApJ...873...91G |s2cid=125181833 |doi-access=free }}</ref>

}}

== External links ==
* Jim Kaler's Stars: [https://web.archive.org/web/20051123222352/http://www.astro.uiuc.edu/~kaler/sow/elnath.html Elnath]
* {{APOD |date=5 March 2010 |title=Image of Elnath}}

{{Stars of Auriga}}
{{Stars of Taurus}}
{{Sky|05|26|17.5134|+|28|36|27.494}}

{{Authority control}}

{{DEFAULTSORT:Beta Tauri}}
[[Category:B-type giants]]
[[Category:Mercury-manganese stars]]
[[Category:Taurus (constellation)]]
[[Category:Bayer objects|Tauri, Beta]]
[[Category:Bright Star Catalogue objects|1791]]
[[Category:Durchmusterung objects|BD+28 0795]]
[[Category:Flamsteed objects|Tauri, 112]]
[[Category:Henry Draper Catalogue objects|035497]]
[[Category:Hipparcos objects|025428]]
[[Category:Stars with proper names|Elnath]]
[[Category:Auriga]]