Beta Gruis

{{Short description|Star in the constellation of Grus}} {{Redirect|Tiaki|the Japanese proper name|Chiaki}} {{Starbox begin}} {{Starbox image | image= {{Location mark |image=Grus constellation map.svg|alt=|float=center|width=240 |label=|position=right |mark=Red circle.svg|mark_width=14|mark_link=Beta Gruis|x=413|y=712 }} |caption=Location of β Gruis (circled) }} {{Starbox observe | epoch = J2000 | ra = {{RA|22|42|40.05027}}<ref name=aaa474_2_653/> | dec = {{DEC|−46|53|04.4752}}<ref name=aaa474_2_653/> | appmag_v = 2.0 - 2.3<ref name=jaavso34_2_156/> | constell = Grus }} {{Starbox character | type = AGB<ref name=Eggen1992/> | class = M4.5 III<ref name="galex"/> | b-v = +1.620<ref name=sps1966/> | u-b = +1.757<ref name=sps1966/> | variable = SRb<ref name=jaavso34_2_156/> }} {{Starbox astrometry | radial_v = +1.6<ref name=scfs/> | prop_mo_ra = +135.16<ref name=aaa474_2_653/> | prop_mo_dec = −4.38<ref name=aaa474_2_653/> | parallax = 18.43 | p_error = 0.42 | parallax_footnote = <ref name=aaa474_2_653/> | absmag_v = {{Val|−1.61|0.052}}<ref name=park2013/> }} {{Starbox detail | mass = 2.4<ref name=aaa352_217/> | radius = 154<ref name=McDonald/> | luminosity = {{val|3221|242|fmt=commas}}<ref name=McDonald/> | temperature = {{val|3508|125|fmt=commas}}<ref name=McDonald/> | gravity = 0.4<ref name=mnras223_2_239/> | metal_fe = 0.0<ref name=mnras223_2_239/> | rotational_velocity = | age_myr = 450<ref name=Kaler/> }} {{Starbox catalog | names = Tiaki, Beta Gru, CD−47 14308, FK5 856, HR 8636, HD 214952, HIP 112122, SAO 231258.<ref name=SIMBAD/> }} {{Starbox reference | Simbad = HD+214952 }} {{Starbox end}}

'''Beta Gruis''' ('''β Gruis''', abbreviated '''Beta Gru''', '''β Gru'''), formally named '''Tiaki''' {{IPAc-en|t|i|'|ɑː|k|i}},<ref name="IAU-LSN">{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars | publisher=IAU.org | accessdate=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> is the second brightest star in the southern constellation of Grus. It was once considered the rear star in the tail of the constellation of the (Southern) Fish, Piscis Austrinus: it, with Alpha, Delta, Theta, Iota, and Lambda Gruis, belonged to Piscis Austrinus in medieval Arabic astronomy.<ref name=allen1963/>

== Nomenclature ==

''β Gruis'' (Latinised to ''Beta Gruis'') is the star's Bayer designation.

It bore the traditional Tuamotuan name of ''Tiaki''.<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=7 | title=WG Triennial Report (2015-2018) - Star Names | accessdate=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> In 2016, the IAU organized a Working Group on Star Names (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN) | accessdate=22 May 2016 | 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> to catalog and standardize proper names for stars. The WGSN approved the name ''Tiaki'' for this star on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.<ref name="IAU-LSN"/>

In Chinese, {{lang|zh|鶴}} ({{lang|zh-Latn|Hè}}), meaning ''Crane'', refers to an asterism consisting of Beta Gruis, Alpha Gruis, Epsilon Gruis, Eta Gruis, Delta Tucanae, Zeta Gruis, Iota Gruis, Theta Gruis, Delta² Gruis and Mu¹ Gruis.<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, Beta Gruis itself is known as {{lang|zh|鶴二}} ({{lang|zh-Latn|Hè èr}}, {{langx|en|Second Star of the Crane}}).<ref>{{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=2008-10-25 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref> The Chinese name gave rise to another English name, ''Ke''.<ref>[https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Grus*.html Richard Hinckley Allen: Star Names — Their Lore and Meaning: Grus]</ref>

== Properties == [[File:BetaGruLightCurve.png|thumb|left|A visual band light curve for Beta Gruis, plotted from data published by Otero and Moon (2006).<ref name=jaavso34_2_156/> The inset plot shows the points plotted in red with an expanded scale.]] Beta Gruis is a red giant star<ref name=jaavso34_2_156/> on the asymptotic giant branch<ref name=Eggen1992/> with an estimated mass of about 2.4 times that of the Sun<ref name=aj132_4_1445/> and a surface temperature of approximately 3,500 K, just over half the surface temperature of the Sun.<ref name=McDonald/> This low temperature accounts for the dull red color of an M-type star. The total luminosity is about 3,200 times that of the Sun, and it has 150 times the Sun's radius.<ref name=McDonald/>

It is one of the brightest stars at infrared and near-infrared wavelenghts. At the K band, it is the fifth-brightest star in the night sky.<ref>{{cite web|url=https://simbad.cds.unistra.fr/simbad/sim-sam?Criteria=Kmag+%3C+-3.22&submit=submit+query&OutputMode=LIST&maxObject=10000&CriteriaFile=|title=Kmag < -3.22|website=SIMBAD|access-date=July 1, 2024}}</ref>

Alan William James Cousins announced that Beta Gruis is a variable star in 1952.<ref name="Cousins1952"/> Beta Gruis is a semiregular variable (SRb) star that varies in magnitude by about 0.4. It varies between intervals when it displays regular changes with a 37-day periodicity and times when it undergoes slow irregular variability.<ref name=jaavso34_2_156/> {{clear left}}

==References== {{Reflist|refs=

<ref name="Cousins1952">{{cite journal |last1=Cousins |first1=A. W. J. |title=Bright variable stars in southern hemisphere (second list) |journal=The Observatory |date=April 1952 |volume=72 |pages=86–87 |bibcode=1952Obs....72...86C }}</ref>

<ref name=aaa474_2_653>{{citation | first=F. | last=van Leeuwen |date=November 2007 | title=Validation of the new Hipparcos reduction | journal=Astronomy and Astrophysics | volume=474 | issue=2 | pages=653–664 | bibcode=2007A&A...474..653V | doi=10.1051/0004-6361:20078357 |arxiv = 0708.1752 | s2cid=18759600 }}</ref>

<ref name=park2013>{{citation | display-authors=1 | last1=Park | first1=Sunkyung | last2=Kang | first2=Wonseok | last3=Lee | first3=Jeong-Eun | last4=Lee | first4=Sang-Gak | title=Wilson-Bappu Effect: Extended to Surface Gravity | journal=The Astronomical Journal | volume=146 | issue=4 | pages=73 | year=2013 | doi=10.1088/0004-6256/146/4/73 | bibcode=2013AJ....146...73P | arxiv=1307.0592 | s2cid=119187733 | postscript=. }}</ref>

<ref name=Kaler>{{Cite web |first=Jim |last=Kaler |title=Beta Gruis |url=http://stars.astro.illinois.edu/sow/betagru.html |access-date=2024-09-21 |website=stars.astro.illinois.edu}}</ref>

<ref name=McDonald>{{Cite journal |last1=McDonald |first1=I. |last2=Zijlstra |first2=A. A. |last3=Watson |first3=R. A. |date=2017-10-01 |title=Fundamental parameters and infrared excesses of Tycho-Gaia stars |bibcode=2017MNRAS.471..770M |journal=Monthly Notices of the Royal Astronomical Society |volume=471 |issue=1 |pages=770–791 |doi=10.1093/mnras/stx1433 |doi-access=free |arxiv=1706.02208 |issn=0035-8711}}</ref>

<ref name=aaa352_217>{{citation | last1=Gondoin | first1=P. | title=Evolution of X-ray activity and rotation on G-K giants | journal=Astronomy and Astrophysics | volume=352 | pages=217–227 |date=December 1999 | bibcode=1999A&A...352..217G }}</ref>

<ref name=scfs>{{citation | display-authors=1 | title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions | journal=Veröff. Astron. Rechen-Inst. Heidelb | volume=35 | last1=Wielen | first1=R. | last2=Schwan | first2=H. | last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H. | last5=Jahreiß | first5=H. | last6=Jährling | first6=R. | publisher=Astronomisches Rechen-Institut Heidelberg | issue=35 | year=1999 | page=1 | bibcode=1999VeARI..35....1W }}</ref>

<ref name=sps1966>{{citation | display-authors=1 | last1=Gutierrez-Moreno | first1=Adelina | last2=Moreno | first2=H. | last3=Stock | first3=J. | last4=Torres | first4=C. | last5=Wroblewski | first5=H. | title=A System of photometric standards | journal=Publ. Dept. Astron. Univ. Chile | publisher=Publicaciones Universidad de Chile, Department de Astronomy | volume=1 | pages=1–17 | year=1966 | bibcode=1966PDAUC...1....1G }}</ref>

<ref name=allen1963>{{citation | author-link=Richard Hinckley Allen | last1=Allen | first1=R. H. | year=1963 | title=Star Names: Their Lore and Meaning | edition=rep | publisher=Dover Publications Inc. | location=New York, NY | isbn=0-486-21079-0 | page=[https://archive.org/details/starnamestheirlo00alle/page/238 238] }}</ref>

<ref name=jaavso34_2_156>{{citation | last1=Otero | first1=S. A. | last2=Moon | first2=T. | title=The Characteristic Period of Pulsation of β Gruis | journal=The Journal of the American Association of Variable Star Observers | volume=34 | issue=2 | pages=156–164 |date=December 2006 | bibcode=2006JAVSO..34..156O }}</ref>

<ref name=mnras223_2_239>{{citation | last1=Judge | first1=P. G. | title=Constraints on the Outer Atmospheric Structure of Late Type Giant Stars with IUE Application to Alpha-Tauri K5III and Beta-Gruis M5III | journal=Monthly Notices of the Royal Astronomical Society | volume=223 | issue=2 | page=239 |date=November 1986 | bibcode=1986MNRAS.223..239J | doi = 10.1093/mnras/223.2.239 | doi-access=free }}</ref>

<ref name=aj132_4_1445>{{citation | last1=Engelke | first1=Charles W. | last2=Price | first2=Stephan D. | last3=Kraemer | first3=Kathleen E. | title=Spectral Irradiance Calibration in the Infrared. XVI. Improved Accuracy in the Infrared Spectra of the Secondary and Tertiary Standard Calibration Stars | journal=The Astronomical Journal | volume=132 | issue=4 | pages=1445–1463 |date=October 2006 | doi=10.1086/505865 | bibcode=2006AJ....132.1445E | doi-access=free }}</ref>

<ref name=SIMBAD>{{citation | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Beta+Gruis | title =V* bet Gru -- Variable Star | publisher=Centre de Données astronomiques de Strasbourg | work=SIMBAD | accessdate=2010-01-05 }}</ref>

<ref name="galex">{{Cite journal |last1=Răstău |first1=V. |last2=Mečina |first2=M. |last3=Kerschbaum |first3=F. |last4=Olofsson |first4=H. |last5=Maercker |first5=M. |last6=Drechsler |first6=M. |last7=Strottner |first7=X. |last8=Mulato |first8=L. |date=2023-12-01 |title=Extended far-UV emission surrounding asymptotic giant branch stars as seen by GALEX |journal=Astronomy & Astrophysics |language=en |volume=680 |pages=A12 |doi=10.1051/0004-6361/202346120 |issn=0004-6361|arxiv=2310.09056 |bibcode=2023A&A...680A..12R }}</ref>

<ref name=Eggen1992>{{cite journal | last1=Eggen | first1=Olin J. | title=Asymptotic giant branch stars near the sun | journal=Astronomical Journal | volume=104 | issue=1 | date=July 1992 | pages=275–313 | doi=10.1086/116239 | bibcode=1992AJ....104..275E }}</ref>

}}

==External links== *[http://encarta.msn.com/encyclopedia_761587671/beta_gruis.html MSN Encarta] {{Webarchive|url=https://web.archive.org/web/20090829003314/http://encarta.msn.com/encyclopedia_761587671/Beta_Gruis.html |date=2009-08-29 }} ([https://web.archive.org/web/20090829003314/http://encarta.msn.com/encyclopedia_761587671/Beta_Gruis.html Archived] 2009-10-31)

Category:M-type giants Category:Semiregular variable stars Category:Asymptotic-giant-branch stars Category:Grus (constellation) Gruis, Beta Category:Durchmusterung objects 214952 112122 8636 Tiaki Gruis, 057 Category:Brightest stars