Editing Alpha Pavonis

{{Short description|Star in the southern constellation Pavo}}
{{Starbox begin
| name=α Pavonis
}}
{{Starbox image
 | image=
{{Location mark
|image=Pavo constellation map.svg|alt=|float=center|width=280
|label=|position=right
|mark=Red circle.svg|mark_width=10|mark_link=α Pav
|x=288|y=74
}}
|caption=Location of α Pavonis (circled)
}}
{{Starbox observe
| epoch=J2000
| ra = {{RA|20|25|38.85705}}<ref name=aaa474_2_653/>
| dec = {{DEC|−56|44|06.3230}}<ref name=aaa474_2_653/>
| appmag_v = 1.94<ref name=aass34_1/>
| constell = [[Pavo (constellation)|Pavo]]
}}
{{Starbox character
| class = B3 V<ref name=gahm/>
| b-v = −0.20<ref name=aass34_1/>
| u-b = −0.71<ref name=aass34_1/>
| variable =
}}
{{Starbox astrometry
| radial_v = +2.0<ref name=wilson1953/>
| prop_mo_ra = 6.90<ref name=aaa474_2_653/>
| prop_mo_dec = −86.02<ref name=aaa474_2_653/>
| parallax = 18.24
| p_error = 0.52
| parallax_footnote = <ref name=aaa474_2_653/>
| absmag_v = &minus;1.762<ref name=bell/>
}}
{{Starbox detail
| mass = 5.91<ref name=david/>
| radius = 4.83<ref name=aa50_369/>
| luminosity = 2,200<ref name=aa50_369/>
| temperature = 17,711<ref name=david/>
| gravity = 3.94<ref name=david/>
| metal_fe =
| rotational_velocity = 16<ref name=david/>
| age_myr = 48<ref name=david/>
}}
{{Starbox catalog
| names=Peacock, [[Cordoba Durchmusterung|CD]]−57°9674, [[FK5]] 764, [[Henry Draper catalogue|HD]] 193924, [[Hipparcos catalogue|HIP]] 100751, [[Bright Star Catalogue|HR]] 7790, [[Smithsonian Astrophysical Observatory Star Catalog|SAO]] 246574<ref name=SIMBAD/>
}}
{{Starbox reference
| Simbad=HD+193924
}}
{{Starbox end}}

'''Alpha Pavonis''' ('''α Pavonis''', abbreviated '''Alpha Pav''', '''α Pav'''), formally named '''Peacock''' {{IPAc-en|'|p|iː|k|Q|k}}, is a [[binary star]] in the southern [[constellation]] of [[Pavo (constellation)|Pavo]], near the border with the constellation [[Telescopium]].

==Nomenclature==

''α Pavonis'' ([[Latinisation of names|Latinised]] to ''Alpha Pavonis'') is the star's [[Bayer designation]].

The historical name ''Peacock'' was assigned by [[His Majesty's Nautical Almanac Office]] in the late 1930s during the creation of the [[Air Almanac]], a navigational almanac for the [[Royal Air Force]]. Of the fifty-seven stars included in the new almanac, two had no classical names: Alpha Pavonis and [[Epsilon Carinae]]. The RAF insisted that all of the stars must have names, so new names were invented. Alpha Pavonis was named "Peacock" ('pavo' is Latin for 'peacock') whilst Epsilon Carinae was called "Avior".<ref name=sadler1993/> In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|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)|access-date=22 May 2016}}</ref> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin1.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 1 |access-date=28 July 2016}}</ref> included a table of the first two batches of names approved by the WGSN; which included ''Peacock'' for this star and ''Avior'' for Epsilon Carinae.<ref name="IAU-CSN">{{cite web | 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 language|Chinese]] caused by adaptation of the European southern hemisphere constellations into the Chinese system, {{lang|zh|孔雀}} ({{lang|zh-Latn|Kǒng Qiāo}}), meaning ''[[Chinese constellations#The Southern Asterisms|Peacock]]'', refers to an asterism consisting of α Pavonis, [[Eta Pavonis|η Pavonis]], [[Pi Pavonis|π Pavonis]], [[Nu Pavonis|ν Pavonis]], [[Lambda Pavonis|λ Pavonis]], [[Kappa Pavonis|κ Pavonis]], [[Delta Pavonis|δ Pavonis]], [[Beta Pavonis|β Pavonis]], [[Zeta Pavonis|ζ Pavonis]], [[Epsilon Pavonis|ε Pavonis]] and [[Gamma Pavonis|γ Pavonis]]. Consequently, α Pavonis itself is known as {{lang|zh|孔雀十一}} ({{lang|zh-Latn|Kǒng Qiāo shíyī}}, {{langx|en|the Eleventh Star of Peacock}}.)<ref>{{in lang|zh}} [http://aeea.nmns.edu.tw/2006/0607/ap060730.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 30 日] {{Webarchive|url=https://web.archive.org/web/20110522124207/http://aeea.nmns.edu.tw/2006/0607/ap060730.html |date=2011-05-22 }}</ref>

==Properties==

At an apparent magnitude of 1.94,<ref name=aass34_1/> this is the brightest star in Pavo. Based upon [[parallax]] measurements, this star is about {{Convert|179|ly|pc|abbr=off|lk=on}} distant from the [[Earth]].<ref name=aaa474_2_653/> It has an estimated six times the [[Solar mass|Sun's mass]] and 6 times the [[solar radius|Sun's radius]], but 2,200 times the [[Solar luminosity|luminosity of the Sun]].<ref name=aa50_369/> The [[effective temperature]] of the [[photosphere]] is 17,700&nbsp;K, which gives the star a blue-white hue.<ref name=csiro/> It has a [[stellar classification]] of B3&nbsp;V,<ref name=gahm/> although older studies have often given it a [[subgiant]] [[luminosity class]].<ref name=skiff/> It is classified as B2.5 IV in the [[Bright Star Catalogue]].<ref name=hr/>

Stars with the mass of Alpha Pavonis are believed not to have a [[convection zone]] near their surface. Hence the material found in the [[stellar atmosphere|outer atmosphere]] is not processed by the [[nuclear fusion]] occurring at the core. This means that the surface abundance of elements should be representative of the material out of which it originally formed. In particular, the surface abundance of [[deuterium]] should not change during the star's main sequence lifetime. The measured ratio of deuterium to hydrogen in this star amounts to less than {{nowrap|5 × 10<sup>−6</sup>}}, which suggests this star may have formed in a region with an unusually low abundance of deuterium, or else the deuterium was consumed by some means. A possible scenario for the latter is that the deuterium was burned through while Alpha Pavonis was a [[pre-main-sequence star]].<ref name=aaa201_2_273/>

The system is likely to be a member of the [[Tucana-Horologium association]] that share a common motion through space.<ref name=bell/> The estimated age of this association is 45&nbsp;million years.<ref name=bell/> α Pavonis star has a [[peculiar velocity]] of {{nowrap|13 km s<sup>−1</sup>}} relative to its neighbors.<ref name=mnras410_1_190/>

==Companions==
Three stars have been listed as visual companions to α Pavonis: two ninth magnitude stars at about four [[arc minute]]s; and a 12th magnitude F5 main sequence star at about one arc minute.<ref name=wds/><ref name=gahm/> The two ninth magnitude companions are only 17 [[arc second]]s from each other.<ref name=wds/>

α Pavonis A is a [[spectroscopic binary]] consisting of a pair of stars that orbit around each other with a period of 11.753&nbsp;days.<ref name=aaa201_2_273/> However, in part because the two stars have not been individually [[Optical resolution|resolved]], little is known about the companion except that it has a mass of at least {{solar mass|0.26}}.<ref name=bonavita/> One attempt to model a composite [[stellar spectrum|spectrum]] estimated components with spectral types of B0.5 and B2, and a brightness difference between the two components of 1.3 magnitudes.<ref name=beavers/>

==References==
{{reflist|refs=

<ref name=gahm>{{cite journal|bibcode=1983A&AS...51..143G|title=A study of visual double stars with early type primaries. I - Spectroscopic results|journal=Astronomy and Astrophysics Supplement Series|volume=51|pages=143|last1=Gahm|first1=G. F.|last2=Ahlin|first2=P.|last3=Lindroos|first3=K. P.|year=1983}}</ref>

<ref name=wds>{{cite journal|bibcode=2001AJ....122.3466M|title=The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog|journal=The Astronomical Journal|volume=122|issue=6|pages=3466|last1=Mason|first1=Brian D.|last2=Wycoff|first2=Gary L.|last3=Hartkopf|first3=William I.|last4=Douglass|first4=Geoffrey G.|last5=Worley|first5=Charles E.|year=2001|doi=10.1086/323920|doi-access=free}}</ref>

<ref name=beavers>{{cite journal|bibcode=1980ApJS...44..489B|title=Scanner studies of composite spectra. I - Dwarfs|journal=Astrophysical Journal Supplement Series|volume=44|pages=489|last1=Beavers|first1=W. I.|last2=Cook|first2=D. B.|year=1980|doi=10.1086/190702|doi-access=free}}</ref>

<ref name=aaa474_2_653>{{cite journal | 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=aass34_1>{{citation | last1=Nicolet | first1=B. | year=1978 | title=Photoelectric photometric Catalogue of homogeneous measurements in the UBV System | journal=Astronomy and Astrophysics Supplement Series | volume=34 | pages=1–49 | bibcode=1978A&AS...34....1N }}</ref>

<ref name=SIMBAD>{{citation | title=PEACOCK -- Spectroscopic binary | work=SIMBAD | publisher=[[Centre de Données astronomiques de Strasbourg]] | url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alpha+Pavonis | access-date=2011-12-23 }}</ref>

<ref name=wilson1953>{{citation | last=Wilson | first=Ralph Elmer | year=1953 | title=General catalogue of stellar radial velocities | journal=Washington | publisher=[[Carnegie Institution of Washington]] | bibcode=1953GCRV..C......0W }}</ref>

<ref name=aa50_369>{{citation | last1=Jerzykiewicz | first1=M. | last2=Molenda-Zakowicz | first2=J. | title=Empirical Luminosities and Radii of Early-Type Stars after Hipparcos | journal=Acta Astronomica | volume=50 | pages=369–380 |date=September 2000 | bibcode=2000AcA....50..369J }}</ref>

<ref name=aaa201_2_273>{{citation | display-authors=1 | last1=Vidal-Madjar | first1=A. | last2=Ferlet | first2=R. | last3=Coupry | first3=M. F. | last4=Spite | first4=M. | title=Deuterium in early-type stars - The case of Alpha-Pavonis | journal=Astronomy and Astrophysics | volume=201 | issue=2 | pages=273–275 |date=August 1988 | bibcode=1988A&A...201..273V }}</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 | doi-access=free | bibcode=2011MNRAS.410..190T |arxiv = 1007.4883 | s2cid=118629873 }}</ref>

<ref name=sadler1993>{{citation | last1=Sadler | first1=D. H. | title=A Personal History of H.M. Nautical Almanac Office | page=48 | publisher=Edited and privately published by Wilkins, G. A. | year=1993 | url=http://astro.ukho.gov.uk/nao/history/dhs_gaw/nao_perhist_0802_dhs.pdf | access-date=2013-08-27 | archive-date=2012-04-03 | archive-url=https://web.archive.org/web/20120403214348/http://astro.ukho.gov.uk/nao/history/dhs_gaw/nao_perhist_0802_dhs.pdf | url-status=dead }}</ref>

<ref name=csiro>{{citation|title=The Colour of Stars |date=December 21, 2004 |work=Australia Telescope, Outreach and Education |publisher=[[Commonwealth Scientific and Industrial Research Organisation]] |url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |access-date=2012-01-16 |url-status=dead |archive-url=https://web.archive.org/web/20120222183238/http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html |archive-date=February 22, 2012 }}</ref>

<ref name=david>{{cite journal|bibcode=2015ApJ...804..146D|arxiv=1501.03154|title=The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets|journal=The Astrophysical Journal|volume=804|issue=2|pages=146|last1=David|first1=Trevor J.|last2=Hillenbrand|first2=Lynne A.|year=2015|doi=10.1088/0004-637X/804/2/146|s2cid=33401607}}</ref>

<ref name=bell>{{cite journal|bibcode=2015MNRAS.454..593B|arxiv=1508.05955|title=A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood|journal=Monthly Notices of the Royal Astronomical Society|volume=454|pages=593–614|last1=Bell|first1=Cameron P. M.|last2=Mamajek|first2=Eric E.|last3=Naylor|first3=Tim|year=2015|issue=1|doi=10.1093/mnras/stv1981|doi-access=free |s2cid=55297862}}</ref>

<ref name=bonavita>{{cite journal|bibcode=2016A&A...593A..38B|arxiv=1605.03962|title=SPOTS: The Search for Planets Orbiting Two Stars. II. First constraints on the frequency of sub-stellar companions on wide circumbinary orbits|journal=Astronomy & Astrophysics|volume=593|pages=A38|last1=Bonavita|first1=M.|last2=Desidera|first2=S.|last3=Thalmann|first3=C.|last4=Janson|first4=M.|last5=Vigan|first5=A.|last6=Chauvin|first6=G.|last7=Lannier|first7=J.|year=2016|doi=10.1051/0004-6361/201628231|s2cid=55950739}}</ref>

<ref name=skiff>{{cite journal|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=hr>{{cite book |last1=Hoffleit |first1=D. |last2=Jaschek |first2=C. |year=1991 |title=The Bright star catalogue   |location=New Haven |publisher=Yale University Observatory |bibcode=1991bsc..book.....H}}</ref>

}}

<!-- ==References== -->

==External links==
*[http://stars.astro.illinois.edu/sow/peacock.html Peacock] - Jim Kaler's Stars

{{Stars of Pavo}}

{{DEFAULTSORT:Alpha Pavonis}}
[[Category:Bayer objects|Pavonis, Alpha]]
[[Category:B-type subgiants]]
[[Category:Henry Draper Catalogue objects|193924]]
[[Category:Hipparcos objects|100751]]
[[Category:Bright Star Catalogue objects|7790]]
[[Category:Pavo (constellation)]]
[[Category:Spectroscopic binaries]]
[[Category:Stars with proper names|Peacock]]
[[Category:Durchmusterung objects]]