Beta Hydrae

{{Short description|Double star in the constellation Hydra}} {{Starbox begin | name = β Hydrae }} {{Starbox image | image = {{Location mark | image=Hydra IAU.svg | float=center | width=280 | position=right | mark=Red circle.svg | mark_width=10 | mark_link=β Hya | x%=44.6 | y%=69.1 }} | caption=Location of β Hydrae (circled) }} {{Starbox observe | epoch = [[J2000.0]] | equinox = [[J2000.0]] ([[International Celestial Reference System|ICRS]]) | constell = [[Hydra (constellation)|Hydra]]<ref name=Anderson_Francis_2012/> | ra = {{RA|11|52|54.52149}}<ref name=vanLeeuwen2007/> | dec = {{DEC|−33|54|29.2672}}<ref name=vanLeeuwen2007/> | appmag_v = {{nowrap|4.29 (combined)<ref name=Anderson_Francis_2012/>}} {{nowrap|(4.67 + 5.47)}}<ref name=Fabricius_et_al_2002/> }} {{Starbox character | class = B9IIIp Si<ref name=Molnar1972/> + ? kB8hB8HeA0VSi<ref name=Garrison_Gray_1994/> | r-i = −0.08<ref name=bsc1 /> | b-v = {{val|−0.100|0.003}}<ref name=Anderson_Francis_2012/> | u-b = −0.34<ref name=Anderson_Francis_2012/> | variable = [[Alpha2 Canum Venaticorum variable|α2 CVn]]<ref name=Samus_et_al_2017/> }} {{Starbox astrometry | radial_v = −{{val|1.0|3.7}}<ref name=Anderson_Francis_2012/> | prop_mo_ra = −56.56<ref name=vanLeeuwen2007/> | prop_mo_dec = +0.19<ref name=vanLeeuwen2007/> | parallax = 10.53 | p_error = 0.60 | parallax_footnote = <ref name=vanLeeuwen2007/> | absmag_v = −0.59<ref name=Anderson_Francis_2012/> }} {{Starbox detail | component1 = A | mass = {{val|3.36|0.15}}<ref name=aaa334_181/> | radius = {{val|3.89|0.08}}<ref name=Arcos_et_al_2018/> | gravity = {{val|2.52|0.03}}<ref name=Arcos_et_al_2018/> | age_myr = {{val|178|62|12}}<ref name=Sikora_et_al_2019/> | luminosity = {{val|257|45|38}}<ref name=Sikora_et_al_2019/> | temperature = {{val|10980|110|fmt=commas}}<ref name=Arcos_et_al_2018/> | rotational_velocity = | rotation = {{val|2.35666|0.00002|u=days|fmt=commas}}<ref name=Sikora_et_al_2019b/> | component2 = B | mass2 = ~3<ref name=kaler /> }} {{Starbox catalog | names = {{odlist | B=β Hya | name=Beta Hydrae | name2=Beta Hya | name3=[[Double star designation|HJ 4478AB]] | CCDM=J11529-3354AB | CD=−33°8018 | CPD=−33°3159 | GC=16258 | HD=103192 | HIP=57936 | HR=4552 | IDS=11479-3321 AB | PPM=289465 | SAO=202901 | WDS=11529-3354AB }}<ref name=SIMBAD/> }} {{Starbox reference | Simbad = bet+hya | Simbad2 = bet+hya+A|sn2=A | Simbad3 = bet+hya+B|sn3=B }} {{Starbox end}}

[[Image:betaHyaLightCurve.png|thumb|left|[[light curve]] for Beta Hydrae plotted from ''[[Transiting Exoplanet Survey Satellite|TESS]]'' data<ref name=MAST/>]] '''Beta Hydrae''', Latinized from '''β Hydrae''', is a [[double star|double]] [[star]] in the [[celestial equator|equatorial]] [[constellation]] of [[Hydra (constellation)|Hydra]].<ref name=SIMBAD/> Historically, Beta Hydrae was designated '''28 Crateris''', but the latter fell out of use when the [[International Astronomical Union|IAU]] defined the permanent constellation boundaries in 1930.<ref name=Wagman1987/> The system is faintly visible to the naked eye with a combined [[apparent visual magnitude]] that ranges around 4.29.<ref name=Anderson_Francis_2012/> It is located at a distance of approximately 310 [[light year]]s from the [[Sun]] based on [[stellar parallax|parallax]].

The double nature of this system was first reported by English astronomer [[John Herschel]] in 1834.<ref name=Mason_et_al_2014/> The brighter primary, designated component A, has an average visual magnitude of 4.67, while the secondary, component B, is of magnitude 5.47. As of 2002, the secondary is located at an [[angular separation]] of {{val|0.65|ul=arcseconds}} from the primary, along a [[position angle]] of 28.5°.<ref name=Fabricius_et_al_2002/>

The brighter component is an [[Alpha2 Canum Venaticorum variable|α2 Canum Venaticorum variable]] that changes in brightness with a period of 2.344 days and an amplitude of 0.04 in visual magnitude.<ref name=Samus_et_al_2017/> It is a [[stellar magnetic field|magnetic]] [[chemically-peculiar star]]<ref name=Bychkov_et_al_2003/> with an average quadratic field strength of {{val|−206|68|e=−4|ul=T}}.<ref name=Sikora_et_al_2019b/> The star is around 178 million years old<ref name=Sikora_et_al_2019/> with 3.4<ref name=aaa334_181/> times the [[mass of the Sun]] and 3.9<ref name=Arcos_et_al_2018/> times the [[Sun's radius]]. On average, it is radiating 257<ref name=Sikora_et_al_2019/> times the [[luminosity of the Sun]] from its [[photosphere]] at an [[effective temperature]] of 10,980 K.<ref name=Arcos_et_al_2018/>

In 1972, M. R. Molnar found a [[stellar classification]] of B9IIIp Si for β Hydrae A, showing an abundance anomaly for silicon.<ref name=Molnar1972/> R. F. Garrison and R. O. Gray assigned it a class of kB8hB8HeA0VSi in 1994.<ref name=Garrison_Gray_1994/> This notation indicates the [[Calcium K line]] matches a star of class B8, the [[hydrogen lines]] also match a B8 [[stellar spectrum|spectrum]], while the helium lines match an [[A-type main-sequence star]] of class A0V.<ref name=Gray_Corbally_2009/> They noted that the hydrogen lines have "curious rounded profiles".<ref name=Garrison_Gray_1994/> Later studies list abundance anomalies of silicon, chromium, and strontium.<ref name=Mikulášek2007/>

==Cultural significance== The [[Kalapalo people]] of [[Mato Grosso]] state in Brazil called β Hydrae and [[Psi Hydrae|ψ Hya]] ''Kafanifani''.<ref name="basso87"/>

==References== {{Reflist|refs=

<ref name=SIMBAD>{{cite simbad | title=bet hya | access-date=2020-12-31 }}</ref>

<ref name=Sikora_et_al_2019>{{cite journal | title=A volume-limited survey of mCP stars within 100 pc - I. Fundamental parameters and chemical abundances | last1=Sikora | first1=J. | last2=Wade | first2=G. A. | last3=Power | first3=J. | last4=Neiner | first4=C. | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society | volume=483 | issue=2 | pages=2300–2324 | date=February 2019 | arxiv=1811.05633 | bibcode=2019MNRAS.483.2300S | doi=10.1093/mnras/sty3105 | doi-access=free }}</ref>

<ref name=Sikora_et_al_2019b>{{cite journal | title=A volume-limited survey of mCP stars within 100 pc II: rotational and magnetic properties | last1=Sikora | first1=J. | last2=Wade | first2=G. A. | last3=Power | first3=J. | last4=Neiner | first4=C. | display-authors=1 | journal=Monthly Notices of the Royal Astronomical Society | volume=483 | issue=3 | pages=3127–3145 | date=March 2019 | arxiv=1811.05635 | bibcode=2019MNRAS.483.3127S | doi=10.1093/mnras/sty2895 | doi-access=free }}</ref>

<ref name=Mason_et_al_2014>{{citation | title=The Washington Visual Double Star Catalog | 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. | journal=The Astronomical Journal | volume=122 | issue=6 | pages=3466–3471 | year=2014 | bibcode=2001AJ....122.3466M | postscript=. | doi=10.1086/323920 | doi-access=free }}</ref>

<ref name=Arcos_et_al_2018>{{cite journal | title=Stellar parameters and H α line profile variability of Be stars in the BeSOS survey | last1=Arcos | first1=C. | last2=Kanaan | first2=S. | last3=Chávez | first3=J. | last4=Vanzi | first4=L. | last5=Araya | first5=I. | last6=Curé | first6=M. | journal=Monthly Notices of the Royal Astronomical Society | volume=474 | issue=4 | pages=5287–5299 | date=March 2018 | arxiv=1711.08675 | bibcode=2018MNRAS.474.5287A | doi=10.1093/mnras/stx3075 | doi-access=free }}</ref>

<ref name=vanLeeuwen2007>{{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 | arxiv=0708.1752 | doi=10.1051/0004-6361:20078357 | s2cid=18759600 }}</ref>

<ref name=Molnar1972>{{cite journal | title=The Helium-Weak Stars | last=Molnar | first=Michael R. | journal=Astrophysical Journal | volume=175 | page=453 | date=July 1972 | bibcode=1972ApJ...175..453M | doi=10.1086/151570 }}</ref>

<ref name=MAST>{{cite web | 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=Fabricius_et_al_2002>{{cite journal | title=The Tycho double star catalogue | last1=Fabricius | first1=C. | last2=Høg | first2=E. | last3=Makarov | first3=V. V. | last4=Mason | first4=B. D. | last5=Wycoff | first5=G. L. | last6=Urban | first6=S. E. | display-authors=1 | journal=Astronomy and Astrophysics | volume=384 | pages=180–189 | date=2002 | doi=10.1051/0004-6361:20011822|doi-access=free | bibcode=2002A&A...384..180F }}</ref>

<ref name=Wagman1987>{{cite journal | last=Wagman | first=M. | title=Flamsteed's Missing Stars | journal=Journal for the History of Astronomy | issue=3 | volume=18 | page=216 | date=August 1987 | bibcode=1987JHA....18..209W | doi=10.1177/002182868701800305 | s2cid=118445625 }}</ref>

<ref name=Samus_et_al_2017>{{cite journal | 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 | volume=61 | issue=1 | pages=80 | year=2017 | bibcode=2017ARep...61...80S | s2cid=125853869 | doi=10.1134/S1063772917010085 }}</ref>

<ref name=Bychkov_et_al_2003>{{cite journal | title=Catalogue of averaged stellar effective magnetic fields. I. Chemically peculiar A and B type stars | display-authors=1 | last1=Bychkov | first1=V. D. | last2=Bychkova | first2=L. V. | last3=Madej | first3=J. | journal=Astronomy and Astrophysics | volume=407 | pages=631–642 | date=August 2003 | issue=2 | arxiv=astro-ph/0307356 | bibcode=2003A&A...407..631B | doi=10.1051/0004-6361:20030741 | s2cid=14184105 }}</ref>

<ref name=Garrison_Gray_1994>{{cite journal | title=The late B-type stars: refined MK classification, confrontation with Stromgren photometry, and the effects of rotation | last1=Garrison | first1=R. F. | last2=Gray | first2=R. O. | journal=Astronomical Journal | volume=107 | page=1556 | date=April 1994 | bibcode=1994AJ....107.1556G | doi=10.1086/116967 }}</ref>

<ref name=Gray_Corbally_2009>{{cite book | last1=Gray | first1=Richard O. | last2=Corbally | first2=Christopher J. | title=Stellar Spectral Classification | date=2009 | publisher=[[Princeton University Press]] | pages=176–183 | isbn=978-0691125114 }}</ref>

<ref name=Mikulášek2007>{{cite journal | title=On-line database of photometric observations of magnetic chemically peculiar stars | display-authors=1 | last1=Mikulášek | first1=Z. | last2=Janík | first2=J. | last3=Zverko | first3=J. | last4=Žižňovský | first4=J. | last5=Zejda | first5=M. | last6=Netolický | first6=M. | last7=Vaňko | first7=M. | journal=Astronomische Nachrichten | volume=328 | issue=1 | pages=10–15 | date=January 2007 | bibcode=2007AN....328...10M | doi=10.1002/asna.200610705 | doi-access=free }}</ref>

<ref name=bsc1>{{cite web | url=http://webviz.u-strasbg.fr/viz-bin/VizieR-5?-out.add=.&-source=V/50/catalog&recno=4552 | title=HR 4552, database entry | access-date=2020-12-31 | work=The Bright Star Catalogue | edition=5th Revised (Preliminary Version) | first1=D. | last1=Hoffleit | first2=W. H. | last2=Warren, Jr. | publisher=[[Centre de Données astronomiques de Strasbourg]] }} ID [http://vizier.u-strasbg.fr/viz-bin/Cat?V/50 V/50]. Accessed on line September 23, 2008.</ref>

<ref name=aaa334_181>{{cite journal | last=North | first=P. | title=Do SI stars undergo any rotational braking? | journal=Astronomy and Astrophysics | volume=334 | pages=181–187 | date=June 1998 | bibcode=1998A&A...334..181N | arxiv=astro-ph/9802286 }}</ref>

<ref name=kaler>{{cite web | first=James B. | last=Kaler | date=July 4, 2015 | title=Beta Hydrae | work=Stars | url=http://stars.astro.illinois.edu/sow/betahya.html | access-date=2020-12-31 }}</ref>

<ref name="basso87">{{cite book | last=Basso|first=Ellen B. | title=In Favor of Deceit: A Study of Tricksters in an Amazonian Society | publisher=University of Arizona Press | location=Tucson, Arizona| date=1987 | isbn=0-8165-1022-9 | page=[https://archive.org/details/infavorofdeceits0000bass/page/360 360] | url=https://archive.org/details/infavorofdeceits0000bass | url-access=registration }}</ref>

}}

{{Stars of Hydra}}

[[Category:Ap stars]] [[Category:B-type giants]] [[Category:Alpha2 Canum Venaticorum variables]] [[Category:Double stars]]  [[Category:Hydra (constellation)]] [[Category:Bayer objects|Hydrae, Beta]] [[Category:Durchmusterung objects|CD-33 08018]] [[Category:Flamsteed objects|Crateris, 28]] [[Category:Henry Draper Catalogue objects|103192]] [[Category:Hipparcos objects|057936]] [[Category:Bright Star Catalogue objects|4552]]