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{{Starbox begin
| name=Sigma Aquarii
}}{{Starbox image
| image =
| caption = Location of σ Aquarii (circled)
}}{{Starbox observe
| epoch=J2000
| ra = {{RA|22|30|38.81546}}
| dec = {{DEC|–10|40|40.6238}}
| appmag_v = 4.81[3]
| constell = Aquarius
}}{{Starbox character
| class = A0 IVs[4]
| b-v = –0.08[3]
| u-b = –0.14[3]
| variable =
}}{{Starbox astrometry
| radial_v = +11[7]
| prop_mo_ra = +0.30
| prop_mo_dec = –26.87
| parallax = 11.26
| p_error = 1.26
| parallax_footnote =
| absmag_v = {{Val|0.29|0.23}}[11]
}}{{Starbox detail
| mass = 2.87[12]
| radius = 2.87[11]
| luminosity = 105[12]
| temperature = 10,115[12]
| gravity = 4.07[16]
| metal_fe = +0.44[16]
| rotational_velocity = 21[18]
| age_myr = 30[11]
}}{{Starbox catalog
| names = 57 Aquarii, BD–11 5850, FK5 1591, HD 213320, HIP 111123, HR 8573, SAO 165134.[20]
}}{{starbox reference
|Simbad=sig+Aqr}}{{Starbox end}}Sigma Aquarii (σ Aqr, σ Aquarii) is the Bayer designation for a double star in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent visual magnitude of 4.81.[3] Based upon parallax measurements, the distance to this star is roughly {{Convert|290|ly|pc|abbr=off|lk=on}}.Sigma Aquarii has a stellar classification of A0 IVs,[4] indicating that it is a subgiant star. The s qualifier indicates that its absorption lines are sharp (narrow) in comparison with standard stars, caused by relatively slow rotation. It has been categorized as a hot Am star,[24] meaning that it is a chemically peculiar, although this is now considered doubtful.[25] The spectrum displays at least double the normal abundances of elements like magnesium, aluminum and silicon, while helium and scandium are under-abundant. Calcium, normally deficient in Am stars, is has near-normal abundance.[24] The Hipparcos catalogue identified Sigma Aquarii as a possible astrometric binary with an orbital period of 654 days.[27] References1. ^1 2 3 {{citation | display-authors=1 | last1=Gerbaldi | first1=M. | last2=Faraggiana | first2=R. | last3=Burnage | first3=R. | last4=Delmas | first4=F. | last5=Gómez | first5=A. E. | last6=Grenier | first6=S. | title=Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes | journal=Astronomy and Astrophysics Supplement | postscript=. | volume=137 | issue=2 | pages=273–292 |date=June 1999 | doi=10.1051/aas:1999248 | bibcode=1999A&AS..137..273G }}
2. ^1 2 {{citation | last1=Adelman | first1=S. J. | last2=Young | first2=J. M. | last3=Baldwin | first3=H. E. | title=Optical region elemental abundance analyses of B and A stars. II - The hot AM stars Omicron Pegasi and Sigma Aquarii and the marginal peculiar A star Nu CANCRI | journal=Monthly Notices of the Royal Astronomical Society | volume=206 | issue=3 | pages=649–660 |date=February 1984 | bibcode=1984MNRAS.206..649A | postscript=. | doi=10.1093/mnras/206.3.649}}
3. ^1 2 3 4 {{citation | display-authors=1 | last1=Johnson | first1=H. L. | last2=Iriarte | first2=B. | last3=Mitchell | first3=R. I. | last4=Wisniewskj | first4=W. Z. | title=UBVRIJKL photometry of the bright stars | journal=Communications of the Lunar and Planetary Laboratory | volume=4 | issue=99 | pages=99 | year=1966 | bibcode=1966CoLPL...4...99J | postscript=. }}
4. ^1 2 {{citation | display-authors=1 | last1=Cowley | first1=A. | last2=Cowley | first2=C. | last3=Jaschek | first3=M. | last4=Jaschek | first4=C. | title=A study of the bright A stars. I. A catalogue of spectral classifications | journal=Astronomical Journal | volume=74 | pages=375–406 |date=April 1969 | doi=10.1086/110819 | bibcode=1969AJ.....74..375C | postscript=. }}
5. ^1 {{citation | last=Wilson | first=R. E. | year=1953 | title=General Catalogue of Stellar Radial Velocities | journal=Washington | publisher=Carnegie Institute of Washington D.C. | bibcode=1953GCRV..C......0W | postscript=. }}
6. ^1 {{cite simbad | title=* sig Aqr | accessdate=2012-07-04 | postscript=. }}
7. ^1 2 3 {{cite journal|bibcode=2012A&A...537A.120Z|title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities|journal=Astronomy & Astrophysics|volume=537|pages=A120|author1=Zorec|first1=J|last2=Royer|first2=F|year=2012|doi=10.1051/0004-6361/201117691|arxiv=1201.2052}}
8. ^1 {{cite journal|bibcode=2007A&A...463..671R|title=Rotational velocities of A-type stars. III. Velocity distributions|journal=Astronomy and Astrophysics|volume=463|issue=2|pages=671|author1=Royer|first1=F|last2=Zorec|first2=J|last3=Gómez|first3=A. E|year=2007|doi=10.1051/0004-6361:20065224|arxiv=astro-ph/0610785}}
9. ^1 2 {{cite journal|bibcode=2016A&A...589A..83G|title=A new method for the inversion of atmospheric parameters of A/Am stars|journal=Astronomy & Astrophysics|volume=589|pages=A83|author1=Gebran|first1=M|last2=Farah|first2=W|last3=Paletou|first3=F|last4=Monier|first4=R|last5=Watson|first5=V|year=2016|doi=10.1051/0004-6361/201528052|arxiv=1603.01146}}
10. ^1 {{cite journal|bibcode=2009A&A...498..961R|title=Catalogue of Ap, Hg Mn and Am stars|journal=Astronomy and Astrophysics|volume=498|issue=3|pages=961|author1=Renson|first1=P|last2=Manfroid|first2=J|year=2009|doi=10.1051/0004-6361/200810788|url=https://zenodo.org/record/890529/files/article.pdf}}
11. ^1 {{cite journal | author=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=July 1997 | volume=323 | pages=L49–L52 | bibcode=1997A&A...323L..49P }} Note about binarity
}}External links{{Stars of Aquarius}} 10 : Henry Draper Catalogue objects|Bayer objects|Aquarius (constellation)|Astrometric binaries|A-type subgiants|Hipparcos objects|Flamsteed objects|HR objects|Am stars|Durchmusterung objects |