Просмотр кода страницы Английская Википедия:Iota Herculis

{{Английская Википедия/Панель перехода}}
{{Short description|Star in the constellation Hercules}}
{{Starbox begin
 | name=Iota Herculis
}}
{{Starbox image 
 | image = [[File:Hercules Historical View.png|250px]]
 | caption = Historical view of the [[Hercules (constellation)|Hercules]] constellation showing Iota Herculis as one of the hero's feet
}}
{{Starbox observe
 | epoch=J2000 
 | ra={{RA|17|39|27.8864}}<ref name="SIMBAD"/>
 | dec={{DEC|+46|00|22.795}}<ref name="SIMBAD"/>
 | appmag_v=3.80<ref name=szewczuk/>
 | constell=[[Hercules (constellation)|Hercules]]
}}
{{Starbox character 
 | class=B3IV<ref name="SIMBAD"/> 
 | b-v=–0.18<ref name="aaa34"/>
 | u-b=–0.71
 | variable=[[Beta Cephei variable|Beta Cephei]]<ref name=gcvs/>
}} 
{{Starbox astrometry 
 | radial_v=–20.0<ref name="SIMBAD"/>
 | prop_mo_ra=7.48<ref name="LEEUWEN"/>
 | prop_mo_dec=4.53<ref name="LEEUWEN"/>
 | parallax=7.17
 | p_error=0.13
 | parallax_footnote=<ref name="LEEUWEN"/>
 | absmag_v=–1.97<ref name=huang2012/>
}}
{{Starbox detail 
 | mass={{nowrap|6.7 ± 0.1}}<ref name=mnras410_1_190/>
 | radius={{nowrap|5.29 ± 0.45}}<ref name=aj129_3_1642/>
 | luminosity=2,489<ref name=szewczuk/>
 | temperature={{nowrap|18,070 ± 294}}<ref name=aj129_3_1642/>
 | metal_fe=–0.40<ref name="PETERS"/>
 | gravity={{nowrap|3.82 ± 0.06}}<ref name=aj129_3_1642/>
 | rotational_velocity={{val|6|1}}<ref name=szewczuk/>
 | age_myr={{nowrap|37.8 ± 8.6}}<ref name=mnras410_1_190/>
}}
{{Starbox catalog
 | names=[[Bayer designation|ι Her]], [[Flamsteed designation|85&nbsp;Her]], [[Harvard Revised catalogue|HR]]&nbsp;6588, [[Bonner Durchmusterung|BD]] +46° 2349, [[Henry Draper Catalogue|HD]]&nbsp;160762, [[FK5]]&nbsp;663, [[Hipparcos catalogue|HIP]]&nbsp;86414, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;46872, [[Boss General Catalogue|GC]]&nbsp;23965, [[Catalog of Components of Double and Multiple Stars|CCDM]]&nbsp;J17395+4601A
}}
{{Starbox reference
 | Simbad=HD+160762
}}
{{Starbox end}}	

'''Iota Herculis''' (ι Herculis, ι Her) is a fourth-magnitude [[variable star]] system in the [[constellation]] [[Hercules (constellation)|Hercules]], consisting of at least four [[star]]s all about {{convert|139|pc|ly|abbr=off|lk=on}} away. The brightest is a [[β Cephei variable]], a pulsating star.

== Visibility ==
[[File:Precession N.gif|left|thumb|The path of the north celestial pole among the stars due to the precession. Vega is the brightest star near the bottom, Iota Herculis is to the right near the −10,000 [[hatch mark]].|alt=Small white disks representing the northern stars on a black background, overlaid by a circle showing the position of the north pole over time]]
Iota Herculis is dim enough that in cities with a lot of [[light pollution]] it is unlikely to be visible with the naked eye. In rural areas it will usually be visible, and for much of the [[Northern Hemisphere]] the star is [[circumpolar star|circumpolar]] and visible year around.

===Pole star===
As a visible star, the proximity of Iota Herculis to the [[Precession|precessional path]] the Earth's [[North Pole]] traces across the [[celestial sphere]] makes it a [[pole star]], a title currently held by [[Polaris]]. In 10,000 BCE it was the pole star, and in the future it will be again. While Polaris is only 0.5° off the precessional path Iota Herculis is 4° off.

{| class="wikitable" style="margin: 1em auto 1em auto;"
! width="120" align="center"|Preceded by
! width="160" align="center"|[[Pole star]]
! width="120" align="center"|Succeeded by
|-
|align="center"|'''[[Vega]]'''
|align="center"|~16,000 CE
|align="center"|'''[[Tau Herculis]]'''
|}

== Properties ==
Iota Herculis is a [[B-type star|B-type]] [[subgiant]] star that is at the end of its hydrogen fusion stage.<ref name="KALER"/> With a [[stellar classification]] B3IV, it is considerably larger than the [[Sun]], having a [[solar mass|mass]] that is 6.5 times solar and a [[solar radius|radius]] 5.3 times. Though its [[apparent magnitude]] is only 3.80, it is 2,500 times more [[solar luminosity|luminous than the Sun]], yielding an [[absolute magnitude]] of −2.11, brighter in fact than the most of the hot B stars in the [[Pleiades]] [[open cluster|open star cluster]]. The ''[[Hipparcos]]'' [[satellite]] mission estimated its distance at roughly 152 parsecs (pc) from [[Earth]], or 496 light-years (ly) away;<ref name="PERRYMAN">{{cite journal
 |author1=Perryman, M. A. C. |author2=Lindegren, L. |author3=Kovalevsky, J. |author4=Hoeg, E. | display-authors=etal
 | title=The HIPPARCOS Catalogue
 | journal=Astronomy and Astrophysics
 | date=1997
 | volume=323
 | pages=L49–L52
 | bibcode=1997A&A...323L..49P
}}</ref> an updated parallax measurement from Floor van Leeuwen in 2007, however, puts the distance at 455 ly with a much tighter error factor of only 8 ly.<ref name="LEEUWEN"/>

==Star system==
Iota Herculis is a [[multiple star]] system. It is a [[spectroscopic binary]] having a 113.8-day period, indicating that its closest component is separated by about {{Val|1|ul=AU}}.<ref name="KALER"/> Another companion can be found at approximately 30 AU from the main star, giving it an [[orbital period]] of about 60 years. Still another star has been identified with a common [[proper motion]] at an [[angular separation]] of 116 [[arcseconds]] and a visual magnitude of 12.1.<ref name="CCDM">{{cite web |title=CCDM (Catalog of Components of Double & Multiple stars (Dommanget+ 2002) |work=[[VizieR]] |publisher=[[Centre de Données astronomiques de Strasbourg]] |url=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?CCDM%20J17395%2b4601A |access-date=2010-06-29}}</ref> This would place it approximately 18,000 AU away, giving it an orbit of about 1 million years.<ref name="KALER"/>

==Etymology==
In [[Chinese language|Chinese]], {{lang|zh|天棓}} ({{lang|zh-Latn|Tiān Bàng}}), meaning ''[[Purple Forbidden enclosure|Celestial Flail]]'', refers to an [[Asterism (astronomy)|asterism]] consisting of ι Herculis, [[ξ Draconis]], [[ν Draconis]], [[β Draconis]] and [[γ Draconis]].<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, ι Herculis itself is known as {{lang|zh|天棓五}} ({{lang|zh-Latn|Tiān Bàng wu}}, {{lang-en|the Fifth Star of Celestial Flail}}).

== References ==
{{reflist|refs=

<ref name=szewczuk>{{cite journal|bibcode=2015MNRAS.450.1585S |title=Identification of pulsational modes in rotating slowly pulsating B-type stars |journal=Monthly Notices of the Royal Astronomical Society |volume=450 |issue=2 |pages=1585 |last1=Szewczuk |first1=W. |last2=Daszyńska-Daszkiewicz |first2=J. |year=2015 |doi=10.1093/mnras/stv715 |arxiv=1504.04490 |doi-access=free }}</ref>

<ref name=gcvs>{{cite journal|bibcode=2009yCat....102025S|title=VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)|journal=VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S|volume=1|pages=B/gcvs|display-authors=etal|last1=Samus|first1=N. N.|last2=Durlevich|first2=O. V.|year=2009}}</ref>

<ref name=aj129_3_1642>{{citation | last1=Fitzpatrick | first1=E. L. | last2=Massa | first2=D. | title=Determining the Physical Properties of the B Stars. II. Calibration of Synthetic Photometry | journal=The Astronomical Journal | volume=129 | issue=3 | pages=1642–1662 |date=March 2005 | doi=10.1086/427855 | bibcode=2005AJ....129.1642F |arxiv = astro-ph/0412542| s2cid=119512018 }}</ref>

<ref name="KALER">{{citation | title=IOTA HER (Iota Herculis) | publisher=University of Illinois | work=Stars | first1=James B. | last1=Kaler | url=http://stars.astro.illinois.edu/sow/iotaher.html | access-date=2010-06-29}}</ref>

<ref name="PETERS">{{citation |last1=Peters | first1=Geraldine J. | last2=Aller | first2=Lawrence H. | title=The Chemical Composition of IOTA Herculis | journal=The Astrophysical Journal | date=1970 | volume= 159 | page=525 | bibcode=1970ApJ...159..525P | doi=10.1086/150328 }}</ref>

<ref name="LEEUWEN">{{citation | title=Hipparcos, the New Reduction | last1=van Leeuwen | first1=F. |date=November 2007 | pages=653–664 | issue=2 | volume=474 | url=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HIP%2086414 | doi=10.1051/0004-6361:20078357 | journal=Astronomy and Astrophysics | bibcode=2007A&A...474..653V | access-date=2010-11-21 |arxiv = 0708.1752| s2cid=18759600 }}</ref>

<ref name="aaa34">{{citation |last1=Mermilliod | first1=J.-C. | title=Compilation of Eggen's UBV data, transformed to UBV (unpublished) | journal=Catalogue of Eggen's UBV Data | pages=0 | date=1986 |quote=origin: SIMBAD |bibcode=1986EgUBV........0M }}</ref>

<ref name="SIMBAD">{{cite web | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=iota+her | title=V* iot Her -- Variable Star of beta Cep type | work=SIMBAD | publisher =Centre de Données astronomiques de Strasbourg | access-date = 2010-06-29}}</ref>

<ref name=mnras410_1_190>{{citation | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=[[Monthly Notices of the Royal Astronomical Society]] | volume=410 | issue=1 | pages=190–200 |date=January 2011 | doi=10.1111/j.1365-2966.2010.17434.x | bibcode=2011MNRAS.410..190T |arxiv = 1007.4883| s2cid=118629873 }}</ref>

<ref name=huang2012>{{citation
 | display-authors=1 | last1=Huang | first1=W.
 | last2=Wallerstein | first2=G. | last3=Stone | first3=M.
 | title=A catalogue of Paschen-line profiles in standard stars
 | journal=Astronomy & Astrophysics
 | volume=547 | pages=A62 | year=2012
 | bibcode=2012A&A...547A..62H | arxiv=1210.7893
 | doi=10.1051/0004-6361/201219804 | s2cid=119286159 | postscript=. }}</ref>

}}

== External links ==
*Jim Kaler's Stars, University of Illinois: [http://stars.astro.illinois.edu/sow/iotaher.html IOTA HER (Iota Herculis)]
*An Atlas of the Universe: [http://www.atlasoftheuniverse.com/orbits.html Multiple Star Orbits]

{{Pole star}}
{{Stars of Hercules}}
{{Sky|17|39|27.8864|+|46|00|22.795|1000000}}

{{DEFAULTSORT:Iota Herculis}}
[[Category:Hercules (constellation)]]
[[Category:Bayer objects|Herculis, Iota]]
[[Category:Multiple stars|4]]
[[Category:Stars with proper names|Tiān Bàng wu]]
[[Category:B-type subgiants]]
[[Category:Spectroscopic binaries]]
[[Category:Slowly pulsating B-type stars]]
[[Category:Flamsteed objects|Herculis, 085]]
[[Category:Hipparcos objects|086414]]
[[Category:Henry Draper Catalogue objects|160762]]
[[Category:Bright Star Catalogue objects|6588]]
[[Category:Durchmusterung objects]]
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[[Категория:Википедия]]
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