{{Short description|Variable star in the constellation Hercules}} {{About-distinguish|ω Herculis|72 Herculis{{!}}w Herculis}} {{Starbox begin | name = ω Herculis }} {{Starbox image | image= {{Location mark |image=Hercules constellation map.svg|alt=|float=center|width=280 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=ω Herculis |x=864|y=886 }} |caption=Location of ω Herculis (circled in red) }} {{Starbox observe | epoch = J2000.0 | equinox = J2000.0 (ICRS) | constell = Hercules<ref name=constellation/> | ra = {{RA|16|25|24.95425}}<ref name=vanLeeuwen2007/> | dec = {{DEC|+14|01|59.7711}}<ref name=vanLeeuwen2007/> | appmag_v = 4.5821<ref name=vanLeeuwen2007/> {{nowrap|(4.58 + 11.5)}}<ref name=Eggleton2008/> }} {{Starbox character | class = A2 Vp CrSr<ref name=Abt1995/> | b-v = +0.00<ref name=Mermilliod1986/> | u-b = +0.01<ref name=Mermilliod1986/> | r-i = | variable = α<sup>2</sup> CVn<ref name=Dubath2011/> }} {{Starbox astrometry | radial_v = {{Val|−5.90|0.74}}<ref name=deBruijne2012/> | prop_mo_ra = +40.86<ref name=vanLeeuwen2007/> | prop_mo_dec = −59.71<ref name=vanLeeuwen2007/> | parallax = 13.04 | p_error = 0.64 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = {{Val|0.29|0.15}}<ref name=King2003/> }} {{Starbox detail | source = | component1 = ω Her A | mass = 2.14<ref name=David2015/> | radius = 3.30<ref name=Shulyak2014/> | luminosity = 70<ref name=Mcdonald2012/> | temperature = {{Val|10052|320|fmt=commas}}<ref name=Prugniel2011/> | gravity = {{Val|3.51|0.35}}<ref name=Prugniel2011/> | metal_fe = {{Val|+0.47|0.15}}<ref name=Prugniel2011/> | rotational_velocity = 55<ref name=Abt2002/> | rotation = 2.951<ref name=Aslanov1987/> d | age_myr = 149<ref name=David2015/> }} {{Starbox catalog | names = Cujam, ω Her, 24 Her, 51 Ser, BD+14°3049, FK5 613, HD 148112, HIP 80463, HR 6117, SAO 102153, WDS J16254+1402AB<ref name=SIMBAD/> }} {{Starbox reference | Simbad = ome+Her }} {{Starbox end}} '''Omega Herculis''' ('''ω Herculis''', abbreviated '''Omega Her''', '''ω Her''') is a binary star<ref name=Eggleton2008/> system in the northern constellation of Hercules. Based upon an annual parallax shift of 13.04 mas as seen from Earth, it is located around 250 light-years from the Sun. It is faintly visible to the naked eye, having a combined apparent visual magnitude of 4.58.<ref name=vanLeeuwen2007/> The system is a candidate for membership in the Ursa Major Moving Group, although this remains uncertain.<ref name=King2003/>
The two components are designated '''Omega Herculis A''' (officially named '''Cujam''' {{IPAc-en|'|k|juː|dZ|@m}}, the traditional name of the system)<ref name="IAU-LSN"/> and '''B'''.
==Nomenclature==
''ω Herculis'' (Latinised to ''Omega Herculis'') is the system's Bayer designation. It previously bore the Flamsteed designation of ''51 Serpentis'' before being added to Hercules.<ref name=Wagman1987/> The designations of the two components as ''Omega Herculis A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).<ref name="planetnaming">{{cite arXiv |title=On the naming convention used for multiple star systems and extrasolar planets |date=2010 |eprint=1012.0707 |class=astro-ph.SR |last1= Hessman |first1=F. V. |last2= Dhillon |first2=V. S. |last3= Winget |first3=D. E. |last4= Schreiber |first4=M. R. |last5= Horne |first5=K. |last6= Marsh |first6=T. R. |last7= Guenther |first7=E. |last8= Schwope |first8=A. |last9= Heber |first9=U. }}</ref>
The system bore the traditional name ''Cujam'' (also written as ''Cajam'' and ''Kajam''), meaning ("club").<ref name=Kaler2013/> In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)<ref name=WGSN/><ref name=WGSN-B/> to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.<ref name="TriRpt18">{{cite web | url=https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf | page=5 | title=WG Triennial Report (2015-2018) - Star Names | access-date=2018-07-14 | archive-date=2019-08-23 | archive-url=https://web.archive.org/web/20190823174756/https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf | url-status=dead }}</ref> It approved the name ''Cujam'' for the component Omega Herculis A on February 1, 2017 and it is now so included in the List of IAU-approved Star Names.<ref name="IAU-LSN"/>
In Chinese, {{lang|zh|斗}} ({{lang|zh-Latn|Dǒu}}), meaning ''Dipper for Liquid'', refers to an asterism consisting of Omega Herculis, ''49 Serpentis'', ''13 Herculis'', 29 Herculis and ''33 Herculis''.<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 name for Omega Herculis itself is {{lang|zh|斗一}} ({{lang|zh-Latn|Dǒu yī}}, {{langx|en|the First Star of Dipper for Liquid}}).<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_c_d.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20090929163750/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_c_d.htm |date=2009-09-29 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>
== Properties ==
The primary, Omega Herculis A, is a chemically peculiar Ap star with a stellar classification of A2 Vp CrSr.<ref name=Abt1995/> The spectrum displays abnormally strong absorption lines of chromium and strontium, and weak lines of calcium and magnesium.<ref name=Abt1995/> An A-type star, it has an estimated 2.14<ref name=David2015/> times the mass of the Sun and 3.30<ref name=Shulyak2014/> times the Sun's radius. The star is around 149<ref name=David2015/> million years old and is radiating 70<ref name=Mcdonald2012/> times the solar luminosity from its photosphere at an effective temperature of 10,052 K.<ref name=Prugniel2011/>
This component is an Alpha<sup>2</sup> Canum Venaticorum variable<ref name=Dubath2011/> with a brightness amplitude of 0.4 magnitude and a 2.951 day phase that presumably matches the rotation period. The pattern of variation shows that there are regions of the star's surface where the concentrations of elements differ. The star also displays short period variations on the order of 2.5 hours.<ref name=Aslanov1987/> It has a mean effective magnetic field value of {{Val|209e−4|ul=T}}.<ref name=Glagolevskij2007/>
The secondary, Omega Herculis B, is a magnitude 11.5 companion star.<ref name=Eggleton2008/> As of 2010, it was located at an angular separation of 0.80 arc seconds along a position angle of 294°.<ref name=WDSC2014/>
==References== <references> <ref name=constellation>{{cite constellation|51 Ser|mode=cs2|postscript=.}}</ref>
<ref name=vanLeeuwen2007>{{citation | title=Validation of the new Hipparcos reduction | last1=van Leeuwen | first1=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | date=2007 | arxiv=0708.1752 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 | s2cid=18759600 | postscript=. }}</ref>
<ref name=WDSC2014>{{citation | display-authors=1 | last1=Mason | first1=B. D. | last2=Wycoff | first2=G. L. | last3=Hartkopf | first3=W. I. | last4=Douglass | first4=G. G. | last5=Worley | first5=C. E. | title=The Washington Visual Double Star Catalog | year=2014 | bibcode=2001AJ....122.3466M | doi=10.1086/323920 | postscript=. | volume=122 | journal=The Astronomical Journal | issue=6 | pages=3466–3471| doi-access=free }}</ref>
<ref name=Dubath2011>{{citation | display-authors=1 | last1=Dubath | first1=P. | last2=Rimoldini | first2=L.| last3=Süveges | first3=M. | last4=Blomme | first4=J.| last5=López | first5=M. | last6=Sarro | first6=L. M.| last7=De Ridder | first7=J. | last8=Cuypers | first8=J.| last9=Guy | first9=L. | last10=Lecoeur | first10=I.| last11=Nienartowicz | first11=K. | last12=Jan | first12=A. | last13=Beck | first13=M. | last14=Mowlavi | first14=N.| last15=De Cat | first15=P. | last16=Lebzelter | first16=T.| last17=Eyer | first17=L. | title=Random forest automated supervised classification of Hipparcos periodic variable stars | journal=Monthly Notices of the Royal Astronomical Society | volume=414 | issue=3 | pages=2602–17 | year=2011 | doi=10.1111/j.1365-2966.2011.18575.x | doi-access=free | bibcode=2011MNRAS.414.2602D | arxiv=1101.2406 | s2cid=118560311 | postscript=. }}</ref>
<ref name=Aslanov1987>{{citation | title=Spectral Variable Star HD148112 - Spectrophotometry of Lines | last1=Aslanov | first1=I. A. | journal=Soviet Astronomy | volume=31 | issue=4 | page=425 | date=August 1987 | bibcode=1987SvA....31..425A | postscript=. }}</ref>
<ref name=King2003>{{citation | display-authors=1 | last1=King | first1=Jeremy R. | last2=Villarreal | first2=Adam R. | last3=Soderblom | first3=David R. | last4=Gulliver | first4=Austin F. | last5=Adelman | first5=Saul J. | title=Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group | journal=The Astronomical Journal | postscript=. | volume=125 | issue=4 | pages=1980–2017 | date=April 2003 | doi=10.1086/368241 | bibcode=2003AJ....125.1980K | url=https://tigerprints.clemson.edu/cgi/viewcontent.cgi?article=1248&context=physastro_pubs | doi-access=free | url-access=subscription }}</ref>
<ref name=Glagolevskij2007>{{citation | title=Magnetic-field dependence of chemical anomalies in CP stars | last1=Glagolevskij | first1=Yu. V. | journal=Astrophysical Bulletin | postscript=. | volume=62 | issue=3 | pages=244–256 | date=September 2007 | doi=10.1134/S1990341307030054 | bibcode=2007AstBu..62..244G | s2cid=122706004 }}</ref>
<ref name=Shulyak2014>{{citation | display-authors=1 | last1=Shulyak | first1=D. | last2=Paladini | first2=C. | last3=Causi | first3=G. Li | last4=Perraut | first4=K. | last5=Kochukhov | first5=O. | title=Interferometry of chemically peculiar stars: Theoretical predictions versus modern observing facilities | journal=Monthly Notices of the Royal Astronomical Society | volume=443 | issue=2 | pages=1629 | year=2014 | postscript=. | bibcode=2014MNRAS.443.1629S | doi=10.1093/mnras/stu1259 | doi-access=free |arxiv = 1406.6093 | s2cid=96452769 }}</ref>
<ref name=Wagman1987>{{citation | last=Wagman | first=M. | title=Flamsteed's Missing Stars | postscript=. | journal=Journal for the History of Astronomy | volume=18 | issue = 3| pages=209–223 |date=August 1987 | bibcode=1987JHA....18..209W | doi=10.1177/002182868701800305 | s2cid=118445625 }}</ref>
<ref name=Kaler2013>{{citation | title=Cujam | work=Stars | publisher=University of Illinois | first=James B. |last=Kaler | date=August 22, 2013 | url=http://stars.astro.illinois.edu/sow/cujam.html | access-date=2016-05-13 | postscript=. }}</ref>
<ref name="IAU-LSN">{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars | publisher=IAU.org | access-date=16 December 2017 | archive-date=10 March 2025 | archive-url=https://web.archive.org/web/20250310063743/https://www.iau.org/public/themes/naming_stars/ | url-status=dead }}</ref>
<ref name=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 | access-date=22 May 2016 | postscript=. | archive-date=10 June 2016 | archive-url=https://web.archive.org/web/20160610172014/https://www.iau.org/science/scientific_bodies/working_groups/280/ | url-status=dead }}</ref>
<ref name=WGSN-B>{{citation | url=https://www.iau.org/news/pressreleases/detail/iau1603/ | title=IAU Formally Approves 227 Star Names | publisher=International Astronomical Union | access-date=24 November 2016 | postscript=. | archive-date=26 November 2016 | archive-url=https://web.archive.org/web/20161126064708/https://www.iau.org/news/pressreleases/detail/iau1603/ | url-status=dead }}</ref>
<ref name=Eggleton2008>{{citation | last1=Eggleton | first1=P. P. | last2=Tokovinin | first2=A. A. | title=A catalogue of multiplicity among bright stellar systems | journal=Monthly Notices of the Royal Astronomical Society | volume=389 | issue=2 | pages=869–879 | date=September 2008 | doi=10.1111/j.1365-2966.2008.13596.x | doi-access=free | bibcode=2008MNRAS.389..869E | postscript=. |arxiv = 0806.2878 | s2cid=14878976 }}</ref>
<ref name=Mcdonald2012>{{citation | display-authors=1 | last1=McDonald | first1=I. | last2=Zijlstra | first2=A. A. | last3=Boyer | first3=M. L. | title=Fundamental Parameters and Infrared Excesses of Hipparcos Stars | journal=Monthly Notices of the Royal Astronomical Society | volume=427 | issue=1 | pages=343–57 | date=2012 | bibcode=2012MNRAS.427..343M | arxiv=1208.2037 | doi=10.1111/j.1365-2966.2012.21873.x | doi-access=free | s2cid=118665352 | postscript=. }}</ref>
<ref name=deBruijne2012>{{citation | last1=de Bruijne | first1=J. H. J. | last2=Eilers | first2=A.-C. | title=Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project | journal=Astronomy & Astrophysics | volume=546 | id=A61 | pages=14 | date=October 2012 | doi=10.1051/0004-6361/201219219 | bibcode=2012A&A...546A..61D | arxiv=1208.3048 | s2cid=59451347 | postscript=. }}</ref>
<ref name=David2015>{{citation | last1=David | first1=Trevor J. | last2=Hillenbrand | first2=Lynne A. | title=The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets | journal=The Astrophysical Journal | volume=804 | issue=2 | pages=146 | year=2015 | bibcode=2015ApJ...804..146D | doi=10.1088/0004-637X/804/2/146 | arxiv=1501.03154 | s2cid=33401607 | postscript=. }}</ref>
<ref name=Prugniel2011>{{citation | display-authors=1 | last1=Prugniel | first1=Ph. | last2=Vauglin | first2=I. | last3=Koleva | first3=M. | title=The atmospheric parameters and spectral interpolator for the MILES stars | journal=Astronomy & Astrophysics | postscript=. | volume=531 | pages=A165 | year=2011 | doi=10.1051/0004-6361/201116769 | arxiv=1104.4952 |bibcode = 2011A&A...531A.165P | s2cid=54940439 }}</ref>
<ref name=Abt1995>{{citation | last1=Abt | first1=Helmut A. | last2=Morrell | first2=Nidia I. | title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars | journal=Astrophysical Journal Supplement | volume=99 | page=135 | date=July 1995 | doi=10.1086/192182 | bibcode=1995ApJS...99..135A | postscript=. | doi-access=free }}</ref>
<ref name=Abt2002>{{citation | display-authors=1 | last1=Abt | first1=Helmut A. | last2=Levato | first2=Hugo | last3=Grosso | first3=Monica | title=Rotational Velocities of B Stars | journal=The Astrophysical Journal | postscript=. | volume=573 | issue=1 | pages=359–365 | date=July 2002 | doi=10.1086/340590 | bibcode=2002ApJ...573..359A | doi-access=free }}</ref>
<ref name=Mermilliod1986>{{citation | last1=Mermilliod | first1=J.-C. | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished) | journal=Catalogue of Eggen's UBV Data | year=1986 | publisher=SIMBAD | bibcode=1986EgUBV........0M | postscript=. }}</ref>
<ref name=SIMBAD>{{cite simbad | title=ome Her | access-date=2017-03-31 }}</ref> </references>
{{Stars of Hercules|state=collapsed}}
{{Sky|16|25|24.953|+|14|01|59.77|1000000}} <!-- Properties -->
Category:A-type main-sequence stars Category:Ap stars Category:Binary stars Category:Ursa Major moving group <!-- Identifiers --> Category:Hercules (constellation) Herculis, Omega Cujam Category:Durchmusterung objects Herculis, 024 148112 080463 6117