Xi Geminorum
{{short description|Star in the constellation Gemini}}
{{Starbox begin
| name = Xi Geminorum
}}
{{Starbox image
| image =
| caption=Location of ξ Geminorum (circled)
}}
{{Starbox observe
| epoch = J2000.0
| constell = Gemini
| dec = {{DEC|+12|53|44.1311}}
}}
{{Starbox character
| r-i =
}}
{{Starbox astrometry
| parallax = 55.56
| p_error = 0.19
}}
{{Starbox detail
| mass = {{nowrap|1.706 ± 0.012}}
| radius = {{nowrap|2.710 ± 0.021}}
| luminosity = {{nowrap|11.574 ± 0.238}}
| temperature = {{nowrap|6,480 ± 39}}
| gravity = {{nowrap|3.81 ± 0.02}}
| metal_fe = {{nowrap|0.00 ± 0.01}}
| rotational_velocity = {{nowrap|66.1 ± 3.3}}
| rotation =
}}
{{Starbox catalog
| names = 31 Geminorum, HR 2484, HD 48737, BD+13°1396, FK5 256, HIP 32362, SAO 96074
}}
{{Starbox reference
| Simbad = Xi+Geminorum
}}
{{Starbox end}}
Xi Geminorum (ξ Geminorum, abbreviated Xi Gem, ξ Gem), formally named Alzirr {{IPAc-en|'|æ|l|z|@r}},{{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 zodiac constellation of Gemini. It forms one of the four feet of the outline demarcating the Gemini twins. The star has an apparent visual magnitude of 3.35, which is bright enough for it to be seen with the naked eye. From stellar parallax measurements, its distance from the Sun can be estimated as {{Convert|58.7|ly|pc|abbr=off|lk=on}}.
Nomenclature
ξ Geminorum (Latinised to Xi Geminorum) is the star's Bayer designation.
It bore the traditional name of Al Zirr or Alzirr, from the Arabic الزِرّ al-zirr "the button". 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 Alzirr for this star on 30 June 2017 and it is now so included in the List of IAU-approved Star Names.
This star, along with Gamma Geminorum (Alhena), Mu Geminorum, Nu Geminorum and Eta Geminorum were al-hanʽah "the brand" (on the neck of the camel). They also were associated in al-nuḥātai, the dual form of al-nuḥāt, "the camel's hump".
In Chinese, {{lang|zh|井宿}} ({{lang|zh-Latn|Jǐng Su}}), meaning Well (asterism), refers to an asterism consisting of Xi Geminorum, Mu Geminorum, Nu Geminorum, Gamma Geminorum, Epsilon Geminorum, 36 Geminorum, Zeta Geminorum and Lambda Geminorum.{{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, Xi Geminorum itself is known as {{lang|zh|井宿四}} ({{lang|zh-Latn|Jǐng Su sì}}, {{langx|en|the Fourth Star of Well}}.){{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=October 25, 2008 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.
Properties
Although generally considered a single star, there is some evidence that Xi Geminorum may instead be a spectroscopic binary system consisting of two component stars of equal mass.
Xi Geminorum has a stellar classification of F5 IV-V, which is subgiant star that is in the process of evolving away from the main sequence of stars like the Sun. It has about 162% of the Sun's mass and is radiating more than 11 times the luminosity of the Sun. This energy is being emitted from the outer envelope of the star at an effective temperature of 6,464 K. This causes the star to take on the yellow-white hue common to F-type stars.
X-ray emission has been detected from this star, which has an estimated X-ray luminosity of {{nowrap|1.06 × 1029 erg s−1}}. It has the spectroscopic signature of a rapidly rotating star, with a projected rotational velocity of about 66 km s−1.
References
{{reflist|refs=
{{citation | display-authors=1 | last1=Fuhrmann | first1=K. | last2=Chini | first2=R. | last3=Hoffmeister | first3=V. H. | last4=Lemke | first4=R. | last5=Murphy | first5=M. | last6=Seifert | first6=W. | last7=Stahl | first7=O. | title=BESO échelle spectroscopy of solar-type stars at Cerro Armazones | journal=Monthly Notices of the Royal Astronomical Society | volume=411 | issue=4 | pages=2311–2318 |date=March 2011 | doi=10.1111/j.1365-2966.2010.17850.x | bibcode=2011MNRAS.411.2311F | doi-access=free }}
{{citation | first1=Stephen James | last1=O'Meara | title=The Caldwell objects | series=Deep-sky companions | publisher=Cambridge University Press | year=2002 | isbn=0-521-82796-5 | page=185 | url=https://books.google.com/books?id=3Hg6YHgx9nAC&pg=PA185 }}
}}
External links
- {{citation | first1=James B. | last1=Kaler | title=Al ZIRR (Xi Geminorum) | work=SIMBAD | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/alzirr.html | access-date=2012-01-20 }}
{{Stars of Gemini}}
{{DEFAULTSORT:Xi Geminorum}}