Lambda Herculis
{{Short description|Star in the constellation Hercules}}
{{Starbox begin
| name=Lambda Herculis
}}
{{Starbox observe
| epoch=J2000
| constell=Hercules
}}
{{Starbox character
| type = red giant branch or red clump
| variable=
}}
{{Starbox astrometry
| parallax=8.2943
| p_error=0.0921
}}
{{Starbox detail
| rotation=
}}
{{Starbox catalog
| names={{odlist | B=λ Her | F=76 Herculis | BD=+26°3034 | FK5=1460 | HD=158899 | HIP=85693 | HR=6526 | SAO=249461 }}
}}
{{Starbox reference
|Simbad=lam+Her
}}
{{Starbox end}}
Lambda Herculis (λ Herculis. abbreviated Lambda Her, λ Her), formally named Maasym {{IPAc-en|'|m|ei|@|s|I|m}},{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |accessdate=16 December 2017}} is a star in the constellation of Hercules. From parallax measurements taken during the Gaia mission, it is approximately 393 light-years from the Sun.
Nomenclature
λ Herculis (Latinised to Lambda Herculis) is the star's Bayer designation.
It bore the traditional name Maasym, from the Arabic مِعْصَم miʽṣam "wrist". In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN){{citation
| url=https://www.iau.org/science/scientific_bodies/working_groups/280/
| title=IAU Working Group on Star Names (WGSN)
| publisher=International Astronomical Union
| accessdate=22 May 2016 | postscript=. }} to catalogue and standardize proper names for stars. The WGSN approved the name Maasym for this star on 12 September 2016 and it is now so included in the List of IAU-approved Star Names.
In Chinese, {{lang|zh|天市左垣}} ({{lang|zh-Latn|Tiān Shì Zuǒ Yuán}}), meaning Left Wall of Heavenly Market Enclosure, refers to an asterism which represents eleven old states in China and which is marking the left borderline of the enclosure, consisting of Lambda Herculis, Delta Herculis, Mu Herculis, Omicron Herculis, 112 Herculis, Zeta Aquilae, Theta1 Serpentis, Eta Serpentis, Nu Ophiuchi, Xi Serpentis and Eta Ophiuchi.{{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 Chinese name for Lambda Herculis itself is {{lang|zh|天市左垣二}} ({{lang|zh-Latn|Tiān Shì Zuǒ Yuán èr}}, {{langx|en|the Second Star of Left Wall of Heavenly Market Enclosure}}), and represents the state Zhao (or Chaou (趙)),{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_m.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20110130063012/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_m.htm |date=2011-01-30 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm#HeavenlyMarketEnclosure English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name] {{webarchive|url=https://web.archive.org/web/20080924022136/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/e_research_chinengstarzone_b.htm |date=2008-09-24 }}, Hong Kong Space Museum. Accessed on line November 23, 2010. together with 26 Capricorni and 27 Capricorni ("m Capricorni" in R.H.Allen version[https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Capricornus*.html Star Names - R.H.Allen p.142]) in Twelve States (asterism).
Description
Lambda Herculis has an apparent magnitude of 4.4. It has been listed as a standard star for the spectral class spectral class K3.5III, indicating that it is a red giant with a temperature of about {{val|4,000|u=K|fmt=commas}}. Visually it has an absolute magnitude of −0.86, meaning it is nearly 200 times brighter than the sun, but its bolometric luminosity across all wavelengths is over {{solar luminosity|400|link=y}}. It is unclear whether the star is on the red giant branch and fusing hydrogen in a shell or on the horizontal branch (red clump) and fusing helium in its core. As a horizontal-branch star it would be about seven billion years old, but as a red-giant-branch star it would only be about four billion years old.
In 1783, English-German astronomer William Herschel described the solar apex, the point in sky towards which the Solar System is moving; using data from double stars, he identified this position as close to Lambda Herculis. Today it is known the solar apex is not so close to this star, however it is only 10° away from the position currently accepted (in Hercules, southwest of Vega).
References
{{reflist|refs=
{{cite journal |jstor=106492 |last1=Herschel |first1=William |author-link=William Herschel |date=1783 |title=On the Proper Motion of the Sun and Solar System; With an Account of Several Changes That Have Happened among the Fixed Stars since the Time of Mr. Flamstead [sic] |journal=Philosophical Transactions of the Royal Society of London |volume=73 |pages=247–83 |doi=10.1098/rstl.1783.0017 |s2cid=186213288 }}
| 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 | postscript=. }}
{{cite web | title=lam Her -- Variable Star | work=SIMBAD | publisher=Centre de Données astronomiques de Strasbourg | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%402798916&Name=*+lam+Her | accessdate=2010-07-03 }}
{{cite Gaia EDR3|4570796456599587200}}
|arxiv = astro-ph/0409579 |s2cid=17804304 }}
|title=Furud
|first=Jim|last=Kaler
|url=http://stars.astro.illinois.edu/sow/furud.html
|accessdate=2017-04-26}}
{{cite book | first=John | last=Lankford | date=1997 | title=History of astronomy: an encyclopedia | page=[https://archive.org/details/historyofastrono00john/page/258 258] | volume=1 | series=Garland encyclopedias in the history of science | publisher=Taylor & Francis | isbn=0-8153-0322-X | url-access=registration | url=https://archive.org/details/historyofastrono00john/page/258 }}
| last1=De Medeiros | first1=J. R. | last2=Alves |first2=S. | last3=Udry | first3=S | last4=Andersen | first4=J | last5=Nordström | first5=B. | last6=Mayor | first6=M.
| title=A catalog of rotational and radial velocities for evolved stars. V. Southern stars
| journal=Astronomy & Astrophysics | volume=561 | date=January 2014 | pages=27
| bibcode= 2014A&A...561A.126D | arxiv=1312.3474 | doi= 10.1051/0004-6361/201220762| s2cid=54046583 }}
}}
{{Stars of Hercules}}