Gamma Boötis

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Template:Short description

γ Boötis
Template:Location mark
Location of γ Boötis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension Template:RA[1]
Declination Template:DEC[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 Template:Engvar +0.120[4]
B−V Template:Engvar +0.191[4]
Variable type δ Sct[5]
Astrometry
Radial velocity (Rv)Template:Val[6] km/s
Proper motion (μ) RA: −114.344 mas/yr[1]
Dec.: +151.788 mas/yr[1]
Parallax (π)37.9125±0.2550 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)+0.93[4]
Details
Aa
Mass2.10[7] Template:Solar mass
RadiusTemplate:Val[8] Template:Solar radius
Luminosity33.4[9] Template:Solar luminosity
Surface gravity (log g)Template:Val[4] cgs
Temperature7,800[10] K
Metallicity [Fe/H]−0.08[4] dex
Rotational velocity (v sin i)121[10] km/s
Age0.9[4] or 1.0[7] Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[11]
Database references
SIMBADdata

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Gamma Boötis is a binary star[12] system in the northern constellation of Boötes the herdsman, forming the left shoulder of this asterism.[13] Its name is a Bayer designation that is Latinised from γ Boötis, and abbreviated Gamma Boo or γ Boo. The primary component has the proper name Seginus, pronounced Template:IPAc-en,Script error: No such module "Unsubst". the traditional name of the Gamma Bootis system.[14] It has a white hue and is visible to the naked eye with a typical apparent visual magnitude of +3.03.[2] Based on parallax measurements, it is located at a distance of 86 light-years, but is drifting closer to the Sun with a radial velocity of −32 km/s.[6]

Properties

The double nature of this system was discovered by American astronomer S. W. Burnham in 1878, and has the discovery code BU 616.[15] The system is resolved into a pair separated by Template:Val with a brightness difference of 9.7 magnitudes. The brighter primary is itself a close pair separated by Template:Val,[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 Template:Convert.[18] Gamma Boötis' two components are themselves designated WDS J14321+3818Aa (Seginus)[14] and Ab.

File:GammaBooLightCurve.png
A light curve for Gamma Boötis, plotted from TESS data[19]

The stellar classification of Gamma Boötis is A7IV+(n),[2] matching an 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 Template:Convert 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 main sequence or slightly evolved.[4] The primary is around one billion years old with 2.1 times the mass of the Sun[7] and 4.65 times the Sun's radius.[20] Measurements of the projected rotational velocity range from 115 to 145 km/s,[4] suggesting a high rate of spin. On average, the star is radiating 33.4 times the luminosity of the Sun[9] from its photosphere at an effective temperature of Template:Val.[10]

The system displays a statistically significant infrared excess due to a 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 Template:Val.[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).[21]

Gamma Boötis bore the traditional name Ceginus (later Seginus), from cheguius or theguius, apparently Latin mistranscriptions of an Arabic rendering of Greek Boötes.[22] 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,[23] 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.[24]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[25] to catalogue and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[26] 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".[22]

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'.[27]

In Chinese astronomy, Gamma Boötis is called 招搖, Pinyin: Zhāoyáo, meaning Twinkling Indicator, because this star is marking itself and standing alone in Twinkling Indicator asterism, Root mansion (see: Chinese constellation).[28] 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

USS Seginus (AK-133) was a U.S. Navy Crater-class cargo ship named after the star.

References

Template:Reflist

External links

Template:Stars of Boötes

  1. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named GaiaDR3
  2. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named Gray_et_al_2001
  3. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Samus_et_al_2017
  4. ↑ a b c d e f g h i j Cite error: Invalid <ref> tag; no text was provided for refs named Ventura2007
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named mnras309_1_221
  6. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Gontcharov2006
  7. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named DeRosa_et_al_2014
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Baines2025
  9. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named Yelverton_et_al_2019
  10. ↑ a b c d e Cite error: Invalid <ref> tag; no text was provided for refs named Fossati_et_al_2008
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Eggleton_Tokovinin_2008
  13. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Allen1889
  14. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named IAU-LSN
  15. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named WDS
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Morgan_et_al_1978
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBADB
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named GaiaDR3B
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named MAST
  20. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named npoi
  21. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named planetnaming
  22. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named Kunitzsch2006
  23. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Kunitzsch1959
  24. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Laffitte2001
  25. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named WGSN
  26. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named TriRpt18
  27. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Knobel1895
  28. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named zh
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