Gamma Boötis

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γ Boötis
(Seginus system)
Location of γ Boötis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation
Boötes
Right ascension 14h 32m 04.67180s[1]
Declination +38° 18′ 29.7043″[1]
Apparent magnitude (V) +3.03[2]
+3.02 to +3.07[3]
Characteristics
Spectral type A7 IV+(n)[2] or A7 III[4]
U−B color index +0.120[4]
B−V color index +0.191[4]
Variable type δ Sct[5]
Distance
86.8 ± 0.3 ly
(26.61 ± 0.10 pc)
Absolute magnitude (MV)+0.93[4]
Details
Aa
Gyr
BU 616[11]
Database references
SIMBADdata

Gamma Boötis,

apparent visual magnitude of +3.03.[2] Based on parallax measurements obtained during the Hipparcos mission, it is located at a distance of approximately 85 light-years from the Sun, but is drifting closer with a radial velocity of −32 km/s.[6]

Properties

The double nature of this system was discovered by American astronomer

arcseconds with a magnitude difference of 9.27. The brighter primary is itself a close pair separated by 0.069″,[16] as discovered by B. L. Morgan and associates in 1975.[15] The primary or 'A' component of this double star system is designated WDS J14321+3818 ('B' is the star UCAC2 45176266[17]) in the Washington Double Star Catalog. Parallax measurements for component B give a distance of approximately 1,996 light-years.[18] Gamma Boötis' two components are themselves designated WDS J14321+3818Aa (Seginus)[14]
and Ab.

A light curve for Gamma Boötis, plotted from TESS data[19]

The

A-type star with somewhat "nebulous" lines due to rapid rotation. It was found to be a short-period variable star in 1914 by German astronomers P. Guthnick and R. Prager. Non-radial pulsations were detected in 1992 by Edward J. Kennelly and colleagues.[10] It is a Delta Scuti-type variable star with a period of 6.96753 h that varies from magnitude +3.02 down to +3.07.[3] This dominant mode is 21.28 cycles per day with an amplitude of 0.05 in magnitude.[10] Additional pulsations occur at 18.09, 12.02, 11.70 and 5.06 cycles per day.[4]

These types of stars are usually on the

luminosity of the Sun from its photosphere at an effective temperature of 7,800 K.[10]

The system displays a statistically significant

circumstellar disk. A model fit to the data indicates this material has a mean temperature of 85 K and is orbiting at a distance of 99±10 AU.[9]

Nomenclature

γ Boötis (Latinised to Gamma Boötis) is the binary's Bayer designation. WDS J14321+3818 is the wider system's designation in the Washington Double Star Catalog. The designations of the two constituents as WDS J14321+3818A and B, and those of A's components—WDS J14321+3818Aa and Ab—derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[20]

Gamma Boötis bore the traditional name Ceginus (later Seginus), from cheguius or theguius, apparently Latin mistranscriptions of an Arabic rendering of Greek Boötes.[21] Two possibilities have been suggested: from Arabic بوطس bwṭs, in one of the manuscripts of the Almagest, with undotted ب b mistaken for an undotted ث th, و w taken as w and spelled 'gu', and ط ṭ completely misread,[22] or from Arabic بؤوتس bwʾwts, with undotted ب b mistaken for an undotted ث th, ؤ w-hamza mistaken for غ ġ, و w read as u, and undotted ن n misread as an undotted ى y and transcribed i—that is, as th-g-u-i-s with unwritten vowels (and the Latin grammatical ending -us) filled in for theguius.[23]

In 2016, the IAU organized a

multiple systems.[25] It approved the name Seginus for WDS J14321+3818Aa on 21 August 2016 and it is now so included in the List of IAU-approved Star Names.[14]

Gamma Boötis was listed as Haris in Bečvář, apparently derived from the Arabic name of the constellation of Boötes, Al-Haris Al-Sama meaning "the guard of the north".[21]

In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Menkib al Aoua al Aisr (منكب العواء الأيسر – mankibu lʿawwaaʾi lʾaysar), which was translated into Latin as Humerus Sinister Latratoris, meaning 'the left shoulder of barker'.[26]

In

Chinese constellation).[27] 招搖 (Zhāoyáo), westernized into Chaou Yaou, but the name Chaou Yaou was designated for Beta Boötis (Nekkar) by R.H. Allen and the meaning is "to beckon, excite, or move."[13]

Namesake

U.S. Navy Crater-class cargo ship
named after the star.

References

  1. ^
    S2CID 18759600
    .
  2. ^
    doi:10.1086/319956
    .
  3. ^
    S2CID 125853869
    .
  4. ^
    S2CID 14915070
    .
  5. doi:10.1046/j.1365-8711.1999.02821.x
    .
  6. ^
    S2CID 119231169
    .
  7. ^
    doi:10.1093/mnras/stt1932
    .
  8. ^
    doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  9. ^
    doi:10.1093/mnras/stz1927
    .
  10. ^
    S2CID 8543459
    .
  11. ^ "gam Boo", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2016-12-18.
  12. S2CID 14878976
    .
  13. ^
    Allen, Richard Hinckley (1963), Star Names: Their Lore and Meaning
    (Dover ed.), retrieved 2020-12-30.
  14. ^ a b c Naming Stars, IAU.org, retrieved 18 June 2018.
  15. ^
    doi:10.1086/323920
    , retrieved 2020-12-30.
  16. doi:10.1093/mnras/183.4.701
    .
  17. ^ "UCAC2 45176266", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2018-07-24.
  18. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  19. ^ MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 8 December 2021.
  20. Bibcode:2010arXiv1012.0707H
    , 1012.0707.
  21. ^
    ISBN 978-1-931559-44-7
    .
  22. ^ Kunitzsch, Paul (1959), Arabische sternnamen in europa, pp. 152–153.
  23. ^ Laffitte, Roland (2001), Héritages arabes des noms arabes pour les étoiles, p. 160.
  24. ^ IAU working group on star names (WGSN), IAU, retrieved 22 May 2016.
  25. ^ WG Triennial Report (2015-2018) - Star Names (PDF), p. 5, retrieved 2018-07-14.
  26. doi:10.1093/mnras/55.8.429
    .
  27. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 29 日

External links

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