Sigma Hydrae

σ Hydrae (Latinised to Sigma Hydrae) is the system's Bayer designation.

It bore the traditional name Minchir, appearing as Minchir es-schudscha in Bode's large star atlas, Uranographia. The name which derived from the Arabic appelationمنخر الشجاع minkhar ash-shujāʽ "the nostril brave one" (the hydra) for this star. The name is erroneously{{citation needed|date=May 2017}} spelt as Al Minliar al Shuja in the Yale Bright Star Catalogue.{{Cite web|url=http://vizier.u-strasbg.fr/viz-bin/VizieR?-6N&-out.form=H0&//*&-source%3DV/50/notes&HR%3D3418|title = VizieR Service}} 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 Minchir for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.

This star, along with Delta Hydrae (Lisan al Shudja), Epsilon Hydrae, Zeta Hydrae, Eta Hydrae and Rho Hydrae, were Ulug Beg's Min al Azʽal, "Belonging to the Uninhabited Spot".{{cite book | last=Allen | first=R. H. | year=1963 | author-link=Richard Hinckley Allen | title=Star Names: Their Lore and Meaning | url=https://archive.org/details/starnamestheirlo00alle/page/249 | 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/249 249] | url-access=registration }} (According to a 1971 NASA memorandum, Min al Azʽal or Minazal were the title for five stars : Delta Hydrae as Minazal I, Eta Hydrae as Minazal II, Epsilon Hydrae as Minazal III, Rho Hydrae as Minazal IV and Zeta Hydrae as Minazal V.)

In Chinese, {{lang|zh|柳宿}} ({{lang|zh-Latn|Liǔ Sù}}), meaning Willow (asterism), refers to an asterism consisting of Sigma Hydrae, Delta Hydrae, Eta Hydrae, Rho Hydrae, Epsilon Hydrae, Zeta Hydrae, Omega Hydrae and Theta Hydrae.{{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, Sigma Hydrae itself is known as {{lang|zh|柳宿二}} ({{lang|zh-Latn|Liǔ Sù èr}}, {{langx|en|the Second Star of Willow}}).{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0605/ap060528.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 5 月 28 日] {{Webarchive|url=https://web.archive.org/web/20110522112415/http://aeea.nmns.edu.tw/2006/0605/ap060528.html |date=2011-05-22 }}

The people of Groote Eylandt, used the name Unwala ("The Crab") for the star cluster including this star, Delta Hydrae (Lisan al Shudja), Epsilon Hydrae, Zeta Hydrae, Eta Hydrae and Rho Hydrae.

This is an evolved K-type giant star with a stellar classification of K2 III. The measured angular diameter of this star, after correction for limb darkening, is {{Val|2.25|0.03|u=mas}}. At its estimated distance, this yields a physical size of about 27.6 times the radius of the Sun. It has about three times the mass of the Sun and radiates 295 times the solar luminosity from its outer atmosphere at an effective temperature of 4,491 K. Sigma Hydrae is around 430 million years old.

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:$\backslash begin\{align\}\; 2\backslash cdot\; R\_*$

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& \approx 55.2\cdot R_{\bigodot}

\end{align}

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{{Stars of Hydra|state=collapsed}}

{{DEFAULTSORT:Sigma Hydrae}}

Category:K-type giants

Hydrae, Sigma

Category:Hydra (constellation)

Minchir

Category:Durchmusterung objects

Hydrae, 05

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