Alpha Aquarii

From testwiki
Jump to navigation Jump to search

Template:Short description Template:Starbox begin Template:Starbox image Template:Starbox observe Template:Starbox character Template:Starbox astrometry Template:Starbox detail Template:Starbox catalog Template:Starbox reference Template:Starbox end

Alpha Aquarii, officially named Sadalmelik (Template:IPAc-en),[1] is a single yellow supergiant star in the constellation of Aquarius. The apparent visual magnitude of 2.94[2] makes this the second-brightest star in Aquarius. Based upon parallax measurements made by the Gaia spacecraft, it is located at a distance of roughly Template:Convert from the Sun.[3] It is drifting further away from the Sun with a radial velocity of 7.5 km/s.[4]

It forms the primary or 'A' component of a double star designated WDS J22058-0019; the secondary or 'B' component is UCAC2 31789179.[5] However, the pair is only an optical binary, with UCAC2 31789179 being a background star.[5]

Nomenclature

α Aquarii (Latinised to Alpha Aquarii) is the star's Bayer designation. WDS J22058-0019 A is its designation in the Washington Double Star Catalog.

It bore the traditional name Sadalmelik, which derived from an Arabic expression سعد الملك (sa‘d al-malik), meaning "Luck of the king" or “arm/support of God”. The name Rucbah had also been applied to this star; though it shared that name with Delta Cassiopeiae.[6] It is only one of two stars with ancient proper names to lie within a degree of the celestial equator. The origin of the Arabic name is lost to history.[7] In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[8] to catalogue and standardize proper names for stars. The WGSN approved the name Sadalmelik for Alpha Aquarii (WDS J22058-0019 A) on 21 August 2016, and it is now so included in the List of IAU-approved Star Names (Delta Cassiopeiae was given the name Ruchbah).[1]

In Chinese, Template:Lang (Template:Lang), meaning Rooftop (asterism), refers to an asterism consisting of Alpha Aquarii, Theta Pegasi and Epsilon Pegasi.[9] Consequently, the Chinese name for Alpha Aquarii itself is Template:Lang (Template:Lang, Template:Langx).[10]

Properties

With an age of 53 million years,[11] Alpha Aquarii has evolved into a supergiant with a stellar classification of G2 Ib.[11] It lies within the Cepheid instability strip of the Hertzsprung–Russell diagram, near the red (cooler) edge, but is not classified as a variable star. However, variable cores have been detected in the hydrogen lines, which are originating in a circumstellar envelope.[12] The star has a massive stellar wind that reaches supersonic velocity in the chromosphere.[13]

There is some uncertainty about Alpha Aquarii's distance. The original Hipparcos catalog gave a parallax of Template:Val, which translates to a distance of Template:Val, or 760 light-years.[14] However, the 2007 Hipparcos reduction give a parallax that implies a distance of Template:Val, or 520 light-years.[15] The third Gaia data release (Gaia DR3) give a parallax of Template:Val, translating to a distance of Template:Val, or 660 light-years.[16]

Alpha Aquarii's angular diameter has been measured at Template:Val.[17] At its estimated distance,[3] it translates to a radius of Template:Solar radius calculator times the radius of the Sun.[18] With insufficient mass to explode as a supernova, it will most likely become a massive white dwarf similar to Sirius B.[19] It is radiating 3,900 times as much luminosity as the Sun from its outer atmosphere[20] at an effective temperature of Template:Val.[12] At this heat, the star glows with the yellow hue of a G-type star.[21] Examination of this star with the Chandra X-ray Observatory shows it to be significantly X-ray deficient compared to G-type main-sequence stars. This deficit is a common feature of early G-type giant stars.[22]

The visual companion (UCAC2 31789179) has an apparent visual magnitude of approximately 12.2. It is at an angular separation of 110.4 arcseconds from Alpha Aquarii along a position angle of 40°.[23]

References

Template:Reflist

Template:Sky Template:Stars of Aquarius

  1. ↑ 1.0 1.1 Template:Cite web
  2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named saoc8_59
  3. ↑ 3.0 3.1 Cite error: Invalid <ref> tag; no text was provided for refs named b-j
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named scfs
  5. ↑ 5.0 5.1 Template:Citation
  6. ↑ pp. 51, 148, Star-names and Their Meanings, Richard Hinckley Allen, New York: G. E. Stechert, 1899.
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kaler
  8. ↑ Template:Citation
  9. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  10. ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.
  11. ↑ 11.0 11.1 Cite error: Invalid <ref> tag; no text was provided for refs named mnras402_2_1369
  12. ↑ 12.0 12.1 Cite error: Invalid <ref> tag; no text was provided for refs named Usenko_et_al_2017
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Dupree_et_al_1993
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named hipparcos1997
  15. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named DR3
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Baines2023
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named lang2006
  19. ↑ Template:Cite web
  20. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Ayres2023
  21. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named csiro
  22. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named apj627_1_L53
  23. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named wds
Retrieved from "https://en.wiki.beta.math.wmflabs.org/w/index.php?title=Alpha_Aquarii&oldid=11697"