Gamma Boötis

From Wikipedia, the free encyclopedia
(Redirected from Gamma Bootis)
Jump to navigation Jump to search
γ Boötis
Location of γ Boötis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension 14h 32m 04.672s[1]
Declination +38° 18′ 29.69″[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]
Astrometry
Radial velocity (Rv)−32.40±1.0[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]
Distance86.0 ± 0.6 ly
(26.4 ± 0.2 pc)
Absolute magnitude (MV)+0.93[4]
Details
Aa
Mass2.10[7] M☉
Radius4.03±0.04[8] R☉
Luminosity33.4[9] L☉
Surface gravity (log g)3.75±0.05[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
Other designations
Seginus, Haris, Ceginus, Segin, Gamma Boo, 27 Boötis, BD+38°2565, FK5 535, GC 19607, HD 127762, HIP 71075, HR 5435, SAO 64203, PPM 77976, WDS J14321+3818A, BU 616[11]
Database references
SIMBADdata

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 /sɪˈdʒaɪnəs/,[citation needed] 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

[edit | edit source]

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 33.4 arcseconds with a brightness difference of 9.7 magnitudes. 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 1,879 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 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 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 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 7,800 K.[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 99±10 AU.[9]

Nomenclature

[edit | edit source]

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

[edit | edit source]

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

References

[edit | edit source]
  1. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR3 record for this source at VizieR.
  2. ^ a b c d Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  3. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  4. ^ a b c d e f g h i j Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  5. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  6. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  7. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  8. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  9. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  10. ^ a b c d e Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  11. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  12. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  13. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  14. ^ a b c Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  15. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  16. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  17. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  18. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value). Gaia DR3 record for this source at VizieR.
  19. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  20. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  21. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  22. ^ a b Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  23. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  24. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  25. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  26. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  27. ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
  28. ^ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 29 日 Archived 2021-06-05 at the Wayback Machine
[edit | edit source]
Retrieved from "http://70.231.62.181/index.php?title=Gamma_Boötis&oldid=9309056"