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m Journal cites, added 1 DOI using AWB (9904)
 
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{{Starbox begin
42 year old Meat Inspector Filiberto from Haley Station, has hobbies including mountain biking, hay day and fitness. Has toured since childhood and has  visited many locales, such as Nubian Monuments from Abu Simbel to Philae.<br><br>Visit my webpage; [http://hinhnen.chopho.vn/profile/me2358 http://cbi.as/aydayhack37404]
| name = Alpha Herculis
}}
{{Starbox image
| image = [[File:Hercules Historical View.png|250px]]
| caption = Historical view of the [[Hercules (constellation)|Hercules]] constellation showing Rasalgethi as the '''α''' star and "Head of the Kneeler"
}}
{{Starbox observe
| epoch    = J2000
| ra      = {{RA|17|14|38.80}}<ref name=aaa323_L49/><ref name="LEEUWEN"/><ref name="SIMBAD"/>
| dec      = {{DEC| +14|23|25.0}}<ref name=aaa323_L49/><ref name="LEEUWEN"/><ref name="SIMBAD"/>
| appmag_v = 2.9137 / 5.4<ref name=aaa323_L49/><ref name="LEEUWEN"/>
| constell = [[Hercules (constellation)|Hercules]]
}}
{{Starbox character
| class    = M5IIvar / (G5III+F2V)
| b-v      = 1.45<ref name="JOHNSON"/>
| u-b      = 1.01<ref name="JOHNSON"/>
| variable = Semiregular
}}
{{Starbox astrometry
| prop_mo_ra  = -6.71<ref name=aaa323_L49/><ref name="LEEUWEN"/><ref name="SIMBAD"/>
| prop_mo_dec = 32.78<ref name=aaa323_L49/><ref name="LEEUWEN"/><ref name="SIMBAD"/>
| parallax = 9.07
| p_error  = 1.32
| parallax_footnote = <ref name=aaa323_L49/><ref name="LEEUWEN"/>
|absmag_v  = -2.30
}}
{{Starbox detail
| mass  = {{nowrap|2.15 ± 0.22}}<ref name=aaa465_2_593/>
| radius = 387<ref name=aaa465_2_593/>
| luminosity = 8,300<ref name=aaa465_2_593/>
| temperature = 2,800<ref name=aaa465_2_593/>
| metal  =
| gravity = {{nowrap|−0.41 ± 0.19}}<ref name=aaa465_2_593/>
| rotational_velocity =
| age    =
}}
{{Starbox catalog
|names=Ras Algethi, Rasalgethi, [[Bayer designation|α Her]], [[Flamsteed designation|64&nbsp;Her]], [[Harvard Revised catalogue|HR]]&nbsp;6406, [[Bonner Durchmusterung|BD]]&nbsp;+14° 3207, [[Henry Draper Catalogue|HD]]&nbsp;156014J, [[Hipparcos catalogue|HIP]]&nbsp;84345, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]]&nbsp;102680, [[Catalog of Components of Double and Multiple Stars|CCDM]]&nbsp;J17146+1424AB, [[American Association of Variable Star Observers|AAVSO]]&nbsp;1710+14
}}
{{Starbox reference
| Simbad=HD+156014J
}}
{{Starbox end}}
'''Alpha Herculis''' (α Her, α Herculis) is a multiple [[star system]] in the [[constellation]] [[Hercules (constellation)|Hercules]].  It has the traditional name '''Rasalgethi''' or '''Ras Algethi''' ({{lang-ar|رأس الجاثي ra's al-jaθiyy}} ''Head of the Kneeler''), and the [[Flamsteed designation]] '''64 Herculis'''.<ref name="BBC1">{{cite web
  |title=Constellations: Hercules 'the Strongman'
  |publisher=The BBC (British Broadcasting Corporation)
  |author=Kurt Vonnegut
  |url=http://www.bbc.co.uk/dna/h2g2/A29778916
  |accessdate=2010-11-14}}</ref>  The traditional name "Head" comes from the fact that in antiquity Hercules was depicted upside down on the constellation maps.
 
The term ''ra's al-jaθiyy'' or '''Ras al Djathi''' was appeared in the catalogue of stars in the ''Calendarium'' of [[Al Achsasi al Mouakket]], which was translated into [[Latin]] as '''Caput Ingeniculi'''.<ref>{{cite journal
| last=Knobel | first=E. B.
| title=Al Achsasi Al Mouakket, on a catalogue of stars in the Calendarium of Mohammad Al Achsasi Al Mouakket
| journal=Monthly Notices of the Royal Astronomical Society
| volume=55 | page=429 |date=June 1895
| bibcode=1895MNRAS..55..429K }}</ref>
 
In [[Chinese astronomy]], Rasalgethi is called 帝座, [[Pinyin]]: Dìzuò, meaning '' Emperor's Seat'', because this star is marking itself and stand alone in ''Emperor's Seat'' asterism, [[Heavenly Market enclosure]] (see : [[Chinese constellation]]).<ref>{{zh icon}} [http://aeea.nmns.edu.tw/2006/0606/ap060625.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 25 日]</ref> 帝座 (Dìzuò) was westernized into '''Ti Tso''' by R.H. Allen, with the same meaning <ref>[http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Hercules*.html Richard Hinckley Allen: Star Names — Their Lore and Meaning: Hercules]</ref>
 
== Properties ==
The angular diameter of the red giant, α<sup>1</sup> Her, has been measured with an [[interferometer]] as
34&nbsp;±&nbsp;0.8 [[arcsecond|mas]], or 0.034&nbsp;arcseconds.<ref name="BENSON">{{cite journal
  | author=Benson, J. A.; Dyck, H. M.; Mason, W. L.; Howell, R. R.; Ridgway, S. T.; Dixon, D. J.
| title=The infrared angular diameter of Alpha Herculis measured with a Michelson interferometer 
| journal=Astronomical Journal
|date=December 1991
| volume=102
| pages=2091–2097
| doi= 10.1086/116033
| bibcode=1991AJ....102.2091B }}</ref> At an estimated distance of 110 [[parsec]]s from [[Hipparcos]],<ref name=aaa323_L49/><ref name="LEEUWEN"/><ref name=GSM/> this corresponds to a radius of about 280 million kilometers (or 170 million miles), which is roughly 400[[Solar radius|R<sub>☉</sub>]] or 1.87 [[astronomical unit|AU]].<ref name="NOTERADIUS" group="note">To determine the Rasalgheti's radius in terms of solar units, the calculations begin with the formula for [[angular diameter]] as follows:
 
:<math>\begin{smallmatrix} {\delta} = \frac{d_R}{D_R}\end{smallmatrix}</math>
 
where '''''δ''''' equals Rasalgheti's angular diameter in [[arcseconds]], '''''d<sub>R</sub>''''' the star's '''d'''iameter in [[Astronomical Unit|AU]], and '''''D<sub>R</sub>'''''  the '''D'''istance from Earth in parsecs. If we know the angular diameter and the Distance, then we can solve for '''''d<sub>R</sub>''''' as follows:
 
:<math>\begin{smallmatrix}d_R = \delta \cdot D_R = {0.034} \cdot 110.0 = 3.740 AU \end{smallmatrix}</math>.
 
To obtain Rasalgheti's  radius:
 
:<math>\begin{smallmatrix}R_R = {\left ( {\frac {d_R}{2}} \right )} = {\left ( {\frac {3.740}{2}} \right )} = 1.870 AU \end{smallmatrix}</math>.
Converting into Solar units, 1 [[Astronomical Unit|AU]] = 149,597,871&nbsp;km and the mean radius of the [[Sun]] = 696,000&nbsp;km, hence the calculation:
 
:<math>\begin{smallmatrix}d_B = {\left ( 1.87 AU \right )} {\left ( {\frac {149,597,871 km}{696,000 km}} \right )} = 280,000,000 km = 402 R_{\odot} \end{smallmatrix}</math> (rounded).</ref> If Rasalgheti were at the center of our [[Solar System]] its radius would extend past the orbit of [[Mars]] at 1.5 [[astronomical unit|AU]] but not quite as far as the [[asteroid belt]].  The red giant is estimated to have started its life with about 7-8 [[solar mass]]es.<ref name="KALER"/>  Like most [[Stellar classification#Class M|type M]] stars near the end of their lives, Rasalgethi is experiencing a high degree of [[stellar mass loss]] creating a sparse, gaseous envelope that extends at least 90 [[astronomical unit]]s.<ref>{{cite journal
  | last=Deutsch
  | first=Armin J.
  | title=The Circumstellar Envelope of Alpha Herculis
  | journal=Astrophysical Journal
  |date=March 1956
  | volume=123
  | pages=210–227
  | doi=10.1086/146152
  | bibcode=1956ApJ...123..210D}}</ref>
 
== Star system ==
When viewed through a telescope, this system is resolved into two components designated α<sup>1</sup> and α<sup>2</sup>. These two components are more than 500 [[astronomical units]] apart, with an estimated orbital period of approximately 3600 years. α<sup>1</sup> is a relatively massive red [[bright giant]]. α<sup>2</sup> is actually a [[double star]] system with a primary yellow giant star and a secondary, yellow-white dwarf star. (These components are sometimes designated α Herculis A, Ba and Bb, respectively.)
 
==See also==
*[[List of largest known stars]]
*[[Lists of stars]] in the constellation [[List of stars in Hercules|Hercules]]
*[[Betelgeuse#Circumstellar dynamics|Betelgeuse mass loss]]
*[[Stellar classification#Spectral types|Spectral types F, G & M]]
 
== Notes ==
<references group="note" />
 
== References ==
{{reflist|refs=
 
<ref name=aaa465_2_593>{{citation | last1=Schröder | first1=K.-P. | last2=Cuntz | first2=M. | title=A critical test of empirical mass loss formulas applied to individual giants and supergiants | journal=Astronomy and Astrophysics | volume=465 | issue=2 | pages=593–601 |date=April 2007 | doi=10.1051/0004-6361:20066633 | bibcode=2007A&A...465..593S |arxiv = astro-ph/0702172 }}</ref>
 
<ref name="KALER">{{cite web | title=RASALGETHI (Alpha Herculis) | publisher=University of Illinois | first1=James B. | last1=Kaler | url=http://stars.astro.illinois.edu/sow/rasalgethi.html | accessdate=2007-03-07 }}</ref>
 
<ref name="JOHNSON">{{cite journal | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewski | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Comm. Lunar Plan. Lab. | volume=4 | pages=99 | year=1966 | bibcode=1966CoLPL...4...99J }}</ref>
 
<ref name="SIMBAD">{{cite web | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=alpha+her&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id | title =SIMBAD query result:NAME RASALGETHI -- Semi-regular pulsating Star | publisher =Centre de Données astronomiques de Strasbourg | accessdate = 2010-09-26 }}</ref>
 
<ref name=aaa323_L49>{{citation | last1=Perryman | first1=M. A. C. | last2=Lindegren | first2=L. | last3=Kovalevsky | first3=J. |  last4=et al. | title=The Hipparcos Catalogue | journal=Astronomy and Astrophysics | volume=323 |date=July 1997 | pages=L49–L52 | bibcode=1997A&A...323L..49P}}</ref>
 
<ref name="LEEUWEN">{{cite journal | title=Hipparcos, the New Reduction | last1=van Leeuwen | first1=F |date=November 2007 | publisher=[[Centre de Données astronomiques de Strasbourg]] | pages=653 | issue=2 | volume=474 | doi=10.1051/0004-6361:20078357 | journal=Astronomy and Astrophysics | bibcode=2007A&A...474..653V |arxiv = 0708.1752 }}</ref>
 
<ref name=GSM>{{citation | last=Perryman | first=Michael | title=The Making of History's Greatest Star Map | location=Heidelberg | publisher=Springer-Verlag | year=2010 | doi=10.1007/978-3-642-11602-5}}</ref>
 
}}
 
==External links==
*An Atlas of the Universe: [http://www.atlasoftheuniverse.com/orbits.html Multiple Star Orbits]
*Upside down Hercules showing Rasalgethi as the head: [http://www.ne.jp/asahi/stellar/scenes/seiza_e/her.htm Hercules]
 
{{Sky|17|14|38.858|+|14|23|25.20|1000000}}
{{Stars of Hercules}}
 
[[Category:Double stars]]
[[Category:Hercules (constellation)]]
[[Category:Bayer objects|Herculis, Alpha]]
[[Category:Flamsteed objects|Herculis, 64]]
[[Category:Triple star systems]]
[[Category:Stars with proper names]]
[[Category:M-type bright giants]]
[[Category:G-type giants]]
[[Category:F-type main-sequence stars]]
[[Category:Objects within 1000 ly of Earth]]

Latest revision as of 14:59, 19 November 2014

42 year old Meat Inspector Filiberto from Haley Station, has hobbies including mountain biking, hay day and fitness. Has toured since childhood and has visited many locales, such as Nubian Monuments from Abu Simbel to Philae.

Visit my webpage; http://cbi.as/aydayhack37404