Gamma Arietis

{{Short description|Star in the constellation Aries}} {{Starbox begin | name=γ Arietis }} {{Starbox image | image= {{Location mark |image=Aries constellation map.svg|alt=|float=center|width=240 |label=|position=right |mark=Red circle.svg|mark_width=10|mark_link=γ Ari|x=900|y=476 }} |caption=Location of γ Arietis (circled) }} {{Starbox observe | epoch = J2000 | constell = Aries<ref name=xhip/> | ra = {{RA|01|53|31.813}}<ref name=Gaia_DR3/> | dec = {{DEC|+19|17|37.88}}<ref name=Gaia_DR3/> | appmag_v = {{nowrap|3.86 (4.58/4.64)}}<ref name=mnras389_2_869/> }} {{Starbox character | component1 = Gamma¹ Ari (B) | class = {{nowrap|A0Vnp λ Boo<ref name=abt1995/>}} or {{nowrap|A0IV-V(n)kB8<ref name=murphy2015/>}} | b-v = −0.14<ref name=murphy2015/> | u-b = | variable = | component2 = Gamma² Ari (A) | class2 = A2IVpSiSrCr<ref name=abt1984/> | b-v2 = −0.03<ref name=murphy2015/> | u-b2 = | variable2 = α² CVn<ref name=gcvs/> }} {{Starbox astrometry | radial_v = +3.7<ref name=gcsrv/> | prop_mo_ra = +77.138 | prop_mo_dec = −97.321 | pm_footnote = <ref name=Gaia_DR3/> | parallax = 19.6268 | p_error = 0.1526 | parallax_footnote = <ref name=Gaia_DR3/> | absmag_v = −0.10<ref name=xhip/> }} {{Starbox detail | component1 = Gamma¹ Ari (Ba) | mass = 2.67<ref name=ticv8/> | radius = {{val|1.97|0.12}}<ref name="gordon2019"/> | luminosity = 42.0 | temperature = {{val|11000|1100|fmt=commas}}<ref name="gordon2019"/> | gravity = 4.26<ref name=ticv8/> | metal_fe = | rotational_velocity = 54<ref name=aaa393_897/> | age_myr = 34<ref name=gullikson2016/> | component2 = Gamma² Ari (A) | mass2 = 2.72<ref name=ticv8/> | radius2 = 1.941<ref name=ticv8/> | luminosity2 = 41.5 | metal2_fe = {{val|0.43|0.14}}<ref name=aaa525_A71/> | gravity2 = 4.30<ref name=ticv8/> | temperature2= 10,512<ref name=ticv8/> | rotational_velocity2 = 201<ref name=aaa393_897/> }} {{starbox detail|no_heading=y | component1 = Gamma¹ Ari (Bb) | mass = 0.7<ref name=gullikson2016/> | temperature = 4,312<ref name=gullikson2016/> | rotational_velocity = 5<ref name=gullikson2016/> | metal_fe = −0.5<ref name=gullikson2016/> }} {{Starbox catalog | names = {{odlist | F=5 Ari | BD=+18 243 | HIP=8832 | WDS=J01535+1918 }}<ref name=SIMBAD/> | component1 = Gamma¹ Ari (B) | names1 = {{odlist | HD=11502 | HR=545 | SAO=92680 | WDS=J01535+1918B }} | component2 = Gamma² Ari (A) | names2 = {{odlist | HD=11503 | HR=546 | SAO=92681 | WDS=J01535+1918A | GC=2291 }} }} {{Starbox reference | Simbad=gam+Ari|sn=γ Ari | Simbad2=gam01+Ari|sn2=γ¹ Ari (B) | Simbad3=gam02+Ari|sn3=γ² Ari (A) }} {{Starbox end}}

'''Gamma Arietis''' is a binary or possibly trinary star system in the northern constellation of Aries. Its name is a Bayer designation that is Latinized from '''γ Arietis''', and abbreviated '''Gamma Ari''' or '''γ Ari'''. This system is called "The First Star in Aries" as having been at one time the nearest visible star to the equinoctial point. The combined apparent visual magnitude of the stars is 3.86,<ref name=mnras389_2_869/> which is readily visible to the naked eye and makes this the fourth-brightest member of Aries. Based upon parallax measurements,<ref name=Gaia_DR3/> the distance to Gamma Arietis from the Sun is approximately {{Convert|166|ly|pc|abbr=off|lk=on}}.

The two components are designated γ¹ Arietis or Gamma Arietis B and γ²&nbsp;Arietis or Gamma Arietis A. The latter is formally named '''Mesarthim''', pronounced {{IPAc-en|m|ɛ|ˈ|s|ɑr|θ|ɪ|m}}, the traditional name for the Gamma Arietis system. γ¹ Arietis may itself be a spectroscopic binary with a low mass companion.

==Properties== The double star nature of this system was discovered by the English scientist and astronomer Robert Hooke in 1664.<ref name=aitken1935/> The two components have an angular separation of 7.606&nbsp;arcseconds,<ref name=mnras389_2_869/> which can be resolved with a small telescope. The orbital period of the pair is greater than 5,000 years.<ref name=kaler/>

[[File:GammaAriLightCurve.png|thumb|left|A light curve for Gamma Arietis, plotted from ''TESS'' data,<ref name=MAST/> folded with a period of 1.6092 days<ref name="IVSI"/>]] The brighter component, γ² Arietis, is an α² CVn type variable star, a type of star with a strong magnetic field and enhanced spectral lines of some metals, with high chromospheric activity causing brightness changes as the star rotates. Its brightness varies by 0.04 magnitudes with a period of 2.61 days.<ref name=gcvs/> It is also an Ap star, a type of chemically peculiar star with enhanced lines of many metals.<ref name=renson2009/> The spectral class has been given as A2IVpSiSrCr, noting the particular strength of lines of silicon, strontium, and chromium, although other lines such as europium, mercury, and manganese are also stronger than in a normal star. This spectral type suggests that the star is an A2-class subgiant.<ref name=skiff2014/> One study from 2016 identified a low-mass companion to γ² Arietis, a probable red dwarf in a close orbit.<ref name=gullikson2016/>

The marginally fainter of the two visible stars, γ¹ Arietis, is a Lambda Boötis<ref name=aaa412_447/> (chemically peculiar) star with a stellar classification of A0Vnp and a magnitude of 4.64.<ref name=abt1995/> Lambda Boötis stars are identified based on unusually low abundances of iron peak elements in their spectra. This star is spinning rapidly with a projected rotational velocity of 201&nbsp;km/s,<ref name=aaa393_897/> as suggested by the 'n' (nebulosity) notation. The spectral class of this component has also been given as A0IV-V(n)kB8, indicating that calcium K lines in its spectrum are more typical of a B8 star.<ref name=murphy2015/> Older studies often classified it as B9 or B9.5 with a luminosity class of IV or V, indicating either a main sequence or subgiant.<ref name=skiff2014/>

Both of the visible stars have mass of about {{solar mass|2.7|link=y}}, luminosities of about {{solar luminosity|40|link=y}}, effective temperatures of about {{val|10,000|fmt=commas|ul=K}}, and radii of about {{solar radius|2|link=y}}. Their age is about 34 million years.

==Nomenclature==

''γ Arietis'' (Latinised to ''Gamma Arietis'') is the system's Bayer designation; γ¹ and γ² Arietis those of its two components. The designation of the two components as ''Gamma Arietis 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"/>

Gamma Arietis has been called "the First Star in Aries" as having been at one time the nearest visible star to the equinoctial point.

It bore the traditional name ''Mesarthim''. Originally it had shared the name Sheratan with Beta Arietis. However, this got corrupted to "Sartai" in medieval manuscripts, which Bayer erroneously explained as being the Hebrew grammatical term {{lang|hbo|מְשָׁרְתִים}} {{Transliteration|hbo|''mᵉshārᵉthīm''}} "servants", and later scholars picked up on this term.<ref name=Kunitzsch/>

In 2016, the IAU organized a Working Group on Star Names (WGSN)<ref name="WGSN"/> 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"/> It approved the name ''Mesarthim'' for the component ''γ² Arietis'' on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN">{{citation |postscript=. | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}</ref>

In Chinese, {{lang|zh|婁宿}} ({{lang|zh-Latn|Lóusù}}), meaning ''Bond (asterism)'', refers to an asterism consisting of Gamma, Beta and Alpha Arietis.<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 Gamma Arietis itself is {{lang|zh|婁宿二}} ({{lang|zh-Latn|Lóusù Èr}}, {{langx|en|the Second Star of Bond}}).<ref>{{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=January 30, 2011 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>

In Hindu astrology, Gamma Arietis and Beta Arietis (Sheratan) are Ashvins, the twin Rigvedic deities who act as doctors of the divine of the world.<ref name=allen/>

==References== {{reflist|30em|refs=

<ref name=Gaia_DR3>{{cite Gaia DR3|93806419367308544}}</ref>

<ref name=xhip>{{Cite XHIP|8832|mode=cs2|postscript=.}}</ref>

<ref name=allen>{{citation |postscript=. |url=https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Aries*.html |title=Aries |author=Richard H Allen |access-date=2025-04-22 }}</ref>

<ref name=MAST>{{citation |postscript=. |title=MAST: Barbara A. Mikulski Archive for Space Telescopes |url=https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html |publisher=Space Telescope Science Institute |access-date=8 December 2021}}</ref>

<ref name=mnras389_2_869>{{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=aitken1935>{{citation | last1=Aitken | first1=Robert G. | title=The Binary Stars | date=1935 | place=New York | publisher=McGraw-Hill | page=1 | postscript=. }}</ref>

<ref name="IVSI">{{citation |postscript=. |title=gam Ari |url=https://www.aavso.org/vsx/index.php?view=detail.top&oid=3761 |website=The International Variable Star Index |publisher=AAVSO |access-date=3 July 2022}}</ref>

<ref name=gcsrv>{{citation | last=Wilson | first=Ralph Elmer | date=1953 | title=General Catalogue of Stellar Radial Velocities | journal=Carnegie Institute Washington D.C. Publication | publisher=Carnegie Institution of Washington | location=Washington | bibcode=1953GCRV..C......0W | postscript=. }}</ref>

<ref name="gordon2019">{{citation | postscript=. | title=Angular Sizes, Radii, and Effective Temperatures of B-type Stars from Optical Interferometry with the CHARA Array | display-authors=1 | last1=Gordon | first1=Kathryn D. | last2=Gies | first2=Douglas R. | last3=Schaefer | first3=Gail H. | last4=Huber | first4=Daniel | last5=Ireland | first5=Michael | journal=The Astrophysical Journal | volume=873 | issue=1 | page=91 | year=2019 | doi=10.3847/1538-4357/ab04b2 |doi-access=free | bibcode=2019ApJ...873...91G |s2cid=125181833 }}</ref>

<ref name=aaa393_897>{{citation | display-authors=1 | last1=Royer | first1=F. | last2=Grenier | first2=S. | last3=Baylac | first3=M.-O. | last4=Gómez | first4=A. E. | last5=Zorec | first5=J. | title=Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i | journal=Astronomy and Astrophysics | volume=393 | pages=897–911 |date=October 2002 | doi=10.1051/0004-6361:20020943 | bibcode=2002A&A...393..897R | arxiv=astro-ph/0205255 | s2cid=14070763 | postscript=. }}</ref>

<ref name=aaa412_447>{{citation | title=The heterogeneous class of lambda Bootis stars | display-authors=1 | last1=Gerbaldi | first1=M. | last2=Faraggiana | first2=R. | last3=Lai | first3=O. | journal=Astronomy and Astrophysics | volume=412 | issue=2 | pages=447–464 | date=December 2003 | doi=10.1051/0004-6361:20031472 | doi-access=free | bibcode=2003A&A...412..447G | postscript=. }}</ref>

<ref name=aaa525_A71>{{citation | display-authors=1 | last1=Wu | first1=Yue | last2=Singh | first2=H. P. | last3=Prugniel | first3=P. | last4=Gupta | first4=R. | last5=Koleva | first5=M. | title=Coudé-feed stellar spectral library - atmospheric parameters | journal=Astronomy and Astrophysics | volume=525 | page=A71 |date=January 2011 | doi=10.1051/0004-6361/201015014 | bibcode=2011A&A...525A..71W | postscript=. |arxiv = 1009.1491 | s2cid=53480665 }}</ref>

<ref name=SIMBAD>{{cite simbad | title=gam Ari | access-date=2012-08-04 | postscript=. | mode=cs2 }}</ref>

<ref name=kaler>{{citation | first1=James B. | last1=Kaler | title=Mesarthim | work=Stars | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/mesarthim.html | access-date=2012-08-04 | postscript=. }}</ref>

<ref name=abt1984>{{citation | title=The nature of the visual companions of Ap and Am stars | last1=Abt | first1=H. A. | last2=Cardona | first2=O. | journal=Astrophysical Journal, Part 1 | postscript=. | volume=276 | date=January 1, 1984 | pages=266–269 | doi=10.1086/161610 | bibcode=1984ApJ...276..266A }}</ref>

<ref name=gcvs>{{citation | postscript=. | title=General catalogue of variable stars | version=GCVS 5.1 | last1=Samus' | first1=N. N | last2=Kazarovets | first2=E. V | last3=Durlevich | first3=O. V | last4=Kireeva | first4=N. N | last5=Pastukhova | first5=E. N | journal=Astronomy Reports | display-authors=1 | volume=61 | issue=1 | pages=80 | year=2017 | bibcode=2017ARep...61...80S | s2cid=125853869 | doi=10.1134/S1063772917010085 }}</ref>

<ref name=abt1995>{{citation |postscript=. | title=The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars | last1=Abt | first1=Helmut A. | last2=Morrell | first2=Nidia I. | journal=The Astrophysical Journal Supplement Series | volume=99 | pages=135–172 | year=1995 | bibcode=1995ApJS...99..135A | doi=10.1086/192182 | doi-access=free }}</ref>

<ref name=murphy2015>{{citation | title=An Evaluation of the Membership Probability of 212 λ Boo Stars. I. A Catalogue | display-authors=1 | last1=Murphy | first1=Simon J. | last2=Corbally | first2=Christopher J. | last3=Gray | first3=Richard O. | last4=Cheng | first4=Kwang-Ping | last5=Neff | first5=James E. | last6=Koen | first6=Chris | last7=Kuehn | first7=Charles A. | last8=Newsome | first8=Ian | last9=Riggs | first9=Quinlin | journal=Publications of the Astronomical Society of Australia | volume=32 | id=e036 | pages=43 | date=October 2015 | article-number=e036 | doi=10.1017/pasa.2015.34 | bibcode=2015PASA...32...36M | arxiv=1508.03633 | s2cid=59405545 | postscript=. }}</ref>

<ref name=ticv8>{{Citation|postscript=.|display-authors=1|last1=Stassun|first1=Keivan G.|last2=Oelkers|first2=Ryan J.|last3=Paegert|first3=Martin|last4=Torres|first4=Guillermo|last5=Pepper|first5=Joshua|last6=De Lee|first6=Nathan|last7=Collins|first7=Kevin|last8=Latham|first8=David W.|last9=Muirhead|first9=Philip S.|last10=Chittidi|first10=Jay|last11=Rojas-Ayala|first11=Bárbara|date=2019-10-01|title=The Revised TESS Input Catalog and Candidate Target List|bibcode=2019AJ....158..138S|journal=The Astronomical Journal|volume=158|issue=4|pages=138|doi=10.3847/1538-3881/ab3467|arxiv=1905.10694|hdl=1721.1/124721|s2cid=166227927|issn=0004-6256|hdl-access=free|doi-access=free}}</ref>

<ref name=gullikson2016>{{citation | title=The Close Companion Mass-ratio Distribution of Intermediate-mass Stars | display-authors=1 | last1=Gullikson | first1=Kevin | last2=Kraus | first2=Adam | last3=Dodson-Robinson | first3=Sarah | journal=The Astronomical Journal | volume=152 | issue=2 | id=40 | pages=13 | date=August 2016 | doi=10.3847/0004-6256/152/2/40 | bibcode=2016AJ....152...40G | arxiv=1604.06456 | s2cid=119179065 | postscript=. | doi-access=free }}</ref>

<ref name=renson2009>{{citation | last1=Renson | first1=P. | last2=Manfroid | first2=J. | title=Catalogue of Ap, HgMn and Am stars | journal=Astronomy and Astrophysics | volume=498 | issue=3 | pages=961–966 |date=May 2009 | doi=10.1051/0004-6361/200810788 | bibcode=2009A&A...498..961R| doi-access=free |postscript=. }}</ref>

<ref name=skiff2014>{{citation|postscript=.|bibcode=2014yCat....1.2023S|title=VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016)|journal=VizieR On-line Data Catalog: B/Mk. Originally Published in: Lowell Observatory (October 2014)|volume=1|last1=Skiff|first1=B. A.|year=2014}}</ref>

<ref name="planetnaming">{{citation |postscript=. | title=On the naming convention used for multiple star systems and extrasolar planets | display-authors=1 | 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. | year=2010 | arxiv=1012.0707 | bibcode=2010arXiv1012.0707H }}</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=Kunitzsch>{{citation | postscript=. | title=A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations | last1=Kunitzsch | first1=Paul | last2=Smart | first2=Tim | year=2006 | edition=2nd rev. | publisher=Sky Publishing Company | location=Cambridge, Massachusetts | isbn=978-1-931559-44-7 }}</ref>

<ref name="TriRpt18">{{citation | postscript=. | title=WG Triennial Report (2015-2018) – Star Names | publisher=International Astronomical Union | url=https://www.iau.org/static/science/scientific_bodies/working_groups/280/wg-starnames-triennial-report-2015-2018.pdf | page=5 | 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>

}}

==External links== * [http://webviz.u-strasbg.fr/viz-bin/VizieR-S?HR%20545 HR 545] * [http://webviz.u-strasbg.fr/viz-bin/VizieR-S?HR%20546 HR 546] * [https://web.archive.org/web/20080926185552/http://www.purplehell.com/riddletools/stars.htm The Constellations and Named Stars] * [http://aladin.u-strasbg.fr/AladinPreview?-c=01+53+31.80%2B19+17+45.0&ident=HD++11502&submit=Aladin+previewer Image Gamma Arietis] * [http://aladin.u-strasbg.fr/AladinPreview?-c=01+53+31.83%2B19+17+37.2&ident=V*+gam+Ari&submit=Aladin+previewer Image Gamma2 Arietis]

{{Stars of Aries}} {{Authority control}}

<!-- Physical properties -->

Category:A-type main-sequence stars Category:Alpha2 Canum Venaticorum variables Category:A-type subgiants Category:Lambda Boötis stars Category:Binary stars <!-- Catalogues/location --> Category:Aries (constellation) Arietis, Gamma 0545 6 Category:Durchmusterung objects Arietis, 05 011502 008832 Mesarthim Category:Robert Hooke