alpha Pavonis
{{Short description|Star in the southern constellation Pavo}}
{{Starbox begin
| name=α Pavonis
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{{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
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|caption=Location of α Pavonis (circled)
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{{Starbox observe
| epoch=J2000
| dec = {{DEC|−56|44|06.3230}}
| constell = Pavo
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| variable =
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{{Starbox astrometry
| parallax = 18.24
| p_error = 0.52
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| metal_fe =
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{{Starbox catalog
| names=Peacock, CD-57° 9674, FK5 764, HD 193924, HIP 100751, HR 7790, SAO 246574.
}}
{{Starbox reference
| Simbad=HD+193924
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{{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, near the border with the constellation Telescopium.
Nomenclature
α Pavonis (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". In 2016, the International Astronomical Union organized a Working Group on Star Names (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}} to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016{{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}} 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.{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/IAU-CSN.txt | title=IAU Catalog of Star Names |access-date=28 July 2016}}
In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, {{lang|zh|孔雀}} ({{lang|zh-Latn|Kǒng Qiāo}}), meaning Peacock, refers to an asterism consisting of α Pavonis, η Pavonis, π Pavonis, ν Pavonis, λ Pavonis, κ Pavonis, δ Pavonis, β Pavonis, ζ Pavonis, ε Pavonis and 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}}.){{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 }}
Properties
At an apparent magnitude of 1.94, 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. It has an estimated six times the Sun's mass and 6 times the Sun's radius, but 2,200 times the luminosity of the Sun. The effective temperature of the photosphere is 17,700 K, which gives the star a blue-white hue. It has a stellar classification of B3 V, although older studies have often given it a subgiant luminosity class. It is classified as B2.5 IV in the Bright Star Catalogue.
Stars with the mass of Alpha Pavonis are believed not to have a convection zone near their surface. Hence the material found in the 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 × 10−6}}, 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.
The system is likely to be a member of the Tucana-Horologium association that share a common motion through space. The estimated age of this association is 45 million years. α Pavonis star has a peculiar velocity of {{nowrap|13 km s−1}} relative to its neighbors.
Companions
Three stars have been listed as visual companions to α Pavonis: two ninth magnitude stars at about four arc minutes; and a 12th magnitude F5 main sequence star at about one arc minute. The two ninth magnitude companions are only 17 arc seconds from each other.
α Pavonis A is a spectroscopic binary consisting of a pair of stars that orbit around each other with a period of 11.753 days. However, in part because the two stars have not been individually resolved, little is known about the companion except that it has a mass of at least {{solar mass|0.26}}. One attempt to model a composite spectrum estimated components with spectral types of B0.5 and B2, and a brightness difference between the two components of 1.3 magnitudes.
References
{{reflist|refs=
{{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 }}
{{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 }}
{{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 }}
{{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 }}
}}
External links
- [http://stars.astro.illinois.edu/sow/peacock.html Peacock] - Jim Kaler's Stars
{{Stars of Pavo}}
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