epsilon Scorpii
{{short description|Star in the constellation Scorpius}}
{{Starbox begin
| name=ε Scorpii
}}
{{Starbox image
| image=
{{Location mark
|image=Scorpius constellation map.svg
|float=center
|alt=
|label=
|position=right
|width=280
|mark=Red circle.svg
|mark_width=12
|mark_link=ε Scorpii
|x=488|y=620
}}
|caption=Location of ε Sco (circled)
}}
{{Starbox observe
| epoch = J2000
| constell = Scorpius
}}
{{Starbox character
| type = red clump
}}
{{Starbox astrometry
| parallax = 51.19
| p_error = 0.22
| absmag_v = {{val|0.78|0.04}}
}}
{{Starbox detail
| rotational_velocity = {{val|2.6|0.5}}
}}
{{Starbox catalog
| names = Wei, Larawag, 26 Scorpii, CD−34 11285, FK5 628, GCTP 3823.00, Gl 639.1, GJ 9579, HD 151680, HIP 82396, HR 6241, LHS 3244, SAO 208078
}}
{{Starbox reference
| Simbad = eps+Sco
}}
{{Starbox end}}
Epsilon Scorpii (ε Scorpii, abbreviated Eps Sco, ε Sco), formally named Larawag {{IPAc-en|'|l|ær|ə|w|æ|g}},{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |access-date=16 December 2017}} is a star in the southern zodiac constellation of Scorpius. It has an apparent visual magnitude of +2.3, making it the fifth-brightest member of the constellation. Parallax measurements made during the Hipparcos mission provide an estimated distance to this star of around {{Convert|63.7|ly|pc|abbr=off|lk=on}} from the Sun.
Epsilon Scorpii has a stellar classification of K1 III, which indicates it has exhausted the supply of hydrogen at its core and evolved into a giant star. The interferometry-measured angular diameter of this star, after correcting for limb darkening, is {{val|5.99|0.06|ul=mas}}, which, at its estimated distance, equates to a physical radius of nearly 12 times the radius of the Sun. Presently it is generating energy through the nuclear fusion of helium at its core, which, considering the star's composition, places it along an evolutionary branch termed the red clump. The star's outer atmosphere has an effective temperature of 4,560 K, giving it the orange hue of a cool K-type star.
ε Scorpii is classified as a suspected variable star, although a study of Hipparcos photometry showed a variation of no more than 0.01–0.02 magnitudes. It is an X-ray source with a luminosity of {{val|1.5|–|1.6|e=27|u=erg/s}}.
Nomenclature
ε Scorpii (Latinised to Epsilon Scorpii) is the star's Bayer designation.
The star bore the traditional name Larawag in the culture of the Wardaman people of the Northern territory of Australia,{{cite press release |url=https://www.iau.org/news/pressreleases/detail/iau1707/ |title=IAU Approves 86 New Star Names From Around the World |publisher=IAU.org |date=11 December 2017}} meaning clear sighting.{{cite press release |url=http://www.pas.rochester.edu/~emamajek/WGSN/ |title=IAU Working Group on Star Names (WGSN) |publisher=IAU.org}} In 2016, the IAU organized a Working Group on Star Names (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}} to catalog and standardize proper names for stars. The WGSN approved the name Larawag for Epsilon Scorpii on 19 November 2017 and it is now so included in the List of IAU-approved Star Names.
Patrick Moore introduced the name Wei as Chinese name for this star. However, this seems to be a misreading, as Chinese {{lang|zh|尾宿}} ({{lang|zh-Latn|Wěi Xiù}}, English Tail) refers to an asterism (i.e. Chinese constellation) consisting of Epsilon Scorpii, Mu¹ Scorpii, Zeta¹ Scorpii and Zeta² Scorpii, Eta Scorpii, Theta Scorpii, Iota² Scorpii and Iota¹ Scorpii, Kappa Scorpii, Lambda Scorpii and Upsilon Scorpii.{{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}}. Consequently, the name for Epsilon Scorpii itself is {{lang|zh|尾宿二}} ({{lang|zh-Latn|Wěi Xiù èr}}), which means "the Second Star of Tail".{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20081025110153/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_ala_alz.htm |date=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.Ridpath, Ian, [http://www.ianridpath.com/startales/scorpius.htm#chineseStar Tales].
In culture
Epsilon Scorpii appears on the flag of Brazil, symbolising the state of Ceará.{{cite web
|title=Astronomy of the Brazilian Flag
|url=https://flagspot.net/flags/br_astro.html
|publisher=FOTW Flags Of The World website
}}
References
{{reflist|30em|refs=
{{Cite journal |last=Luck |first=R. Earle |date=2015-09-01 |title=Abundances in the Local Region. I. G and K Giants |url=https://ui.adsabs.harvard.edu/abs/2015AJ....150...88L |journal=The Astronomical Journal |volume=150 |issue=3 |pages=88 |doi=10.1088/0004-6256/150/3/88 |issn=0004-6256|arxiv=1507.01466 |bibcode=2015AJ....150...88L }} Epsilon Scorpii's database entries at VizieR: [https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/AJ/150/88&Name=*%20eps%20Sco] [https://vizier.cds.unistra.fr/viz-bin/VizieR?-source=J/AJ/150/88&Key=hip082396]
{{citation | display-authors=1 | last1=Gray | first1=R. O. | last2=Corbally | first2=C. J. | last3=Garrison | first3=R. F. | last4=McFadden | first4=M. T. | last5=Bubar | first5=E. J. | last6=McGahee | first6=C. E. | last7=O'Donoghue | first7=A. A. | last8=Knox | first8=E. R. | title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample | journal=The Astronomical Journal | volume=132 | issue=1 | pages=161–170 |date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G | arxiv=astro-ph/0603770 | s2cid=119476992 }}
{{cite simbad | title=eps Sco | access-date=2012-02-23 }}
}}
{{Stars of Scorpius}}
Category:Horizontal-branch stars