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Alkaid

Koördinate:Sky map13h47m32.4s,+49° 18′ 47.8″
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Alkaid
Alkaid se ligging (in die rooi sirkel).
Alkaid se ligging (in die rooi sirkel).
Sterrebeeld Groot Beer
Bayer-naam Eta Ursae Majoris
Spektraaltipe B3 V[1]
Soort Hoofreeksster
Waarnemingsdata(Epog J2000)
Regte klimming 13h47m32.43776s[2]
Deklinasie +49° 18′ 47.7602″[2]
Skynmagnitude(m) 1,86[3]
Absolute magnitude(M) -0,67[4]
B-V-kleurindeks -0,19[3]
U-B-kleurindeks -0,68[3]
Besonderhede
Massa(M☉) 6,1 ± 0,1[5]
Radius (R☉) 3,4[6]
Ligsterkte(L☉) 594 ± 31[7]
Ouderdom (jaar) 10 ± 2,6miljoen[5]
Temperatuur(K) 15 540 ± 1 157[7]
Rotasiespoed (km/s) 150[8]
Ander name
Benetnash, Benetnasch,[9]Elkeid, 85 Ursae Majoris, BD+50°2027, FK5 509, GC 18643,HD120315,HIP67301,HR5191, PPM 53742, SAO 44752
PortaalPortaalicoon Sterrekunde

Alkaid(ook bekend asEta Ursae Majorisofη UMa) is ’nsterin diesterrebeeldGroot Beer.Dit is die linkerkantste ster van dieasterismeGroot Wa(Big Dipper), maar anders as die meeste sterre van die Groot Beer is dit nie lid van die Ursa Major-groep sterre wat saam deur die lug beweeg nie.[10]Met syskynbare magnitudevan 1,84[11]is Alkaid die derde helderste ster in die sterrebeeld en een van diehelderste sterrein die naglug.

Eienskappe

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Alkaid is ’n 10 miljoen jaar oue[5]B-tipehoofreeksstermet ’nsterreklassifikasievan B3 V.[1]Sedert 1943 dien syspektrumas een van die stabiele ankerpunte waarvolgens ander sterre geklassifiseer word.[12]Symassais ses keer dié van die Son,[5]syradius3,4 keer die Son s’n[6]en syligsterkte594 keer die Son s’n.[7]Syeffektiewe temperatuurvan sowat 15 540K[7]gee dit die tipiese blouwit kleur van ’n B-tipe ster.[13]Die ster straalX-straleuit met ’n helderheid van9,3 × 1028erg s-1.[14]

Alkaid was ’n standaardster vir tipe B3 V. Dit het breëabsorpsielynevanweë sy vinnige rotasie, wat algemeen in sulke sterre is. Die lyne is egter effens verwronge en veranderlik, wat dalk ’n gevolg is van die emissielyne van ’n skyf materiaal wat deur die vinnige rotasie veroorsaak word.[15]

Name

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Die ster seBayer-naamis "Eta Ursae Majoris". Die tradisionele name, "Alkaid" (of "Elkeid" ) en "Benetnasch", kom van dieArabieseقائد بنات نعشqā'id bināt naʿsh,"die leier van die dogters van die doodsbaar". In Julie 2016 het dieInternasionale Astronomiese Uniese sternaamwerkgroep (WGSN) die amptelike naam "Alkaid" vir die ster goedgekeur.[16]

Verwysings

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  1. ↑1,01,1Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification",Annual Review of Astronomy and Astrophysics11:29,doi:10.1146/annurev.aa.11.090173.000333,Bibcode:1973ARA&A..11...29M
  2. ↑2,02,1van Leeuwen, Floor (2007), "Validation of the new Hipparcos reduction",Astronomy and Astrophysics474(2): 653–664,doi:10.1051/0004-6361:20078357,Bibcode:2007A&A...474..653VNota:Sien VizieR-katalogusI/311.
  3. ↑3,03,13,2Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system".CDS/ADC Collection of Electronic Catalogues.2237:0.Bibcode:2002yCat.2237....0D.
  4. ↑Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation",Astronomy Letters38(5): 331,doi:10.1134/S1063773712050015,Bibcode:2012AstL...38..331A.
  5. ↑5,05,15,25,3Tetzlaff, N.; Neuhäuser, R.; Hohle, M. M. (January 2011), "A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun",Monthly Notices of the Royal Astronomical Society410(1): 190–200,doi:10.1111/j.1365-2966.2010.17434.x,Bibcode:2011MNRAS.410..190T
  6. ↑6,06,1Underhill, A. B.et al.(November 1979), "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars",Monthly Notices of the Royal Astronomical Society189(3): 601–605,doi:10.1093/mnras/189.3.601,Bibcode:1979MNRAS.189..601U
  7. ↑7,07,17,27,3Baines, E.; Schmitt, H. R.; Zavala, R. T.; Hutter, D.; van Belle, G. T. (2017), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer",The Astronomical Journal155(1): 30,doi:10.3847/1538-3881/aa9d8b,Bibcode:2018AJ....155...30B
  8. ↑Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars",The Astrophysical Journal573(1): 359–365,doi:10.1086/340590,Bibcode:2002ApJ...573..359A
  9. ↑Rumrill, H. B. (1936). "Star Name Pronunciation".Publications of the Astronomical Society of the Pacific.48(283): 139.Bibcode:1936PASP...48..139R.doi:10.1086/124681.
  10. ↑Motz, Lloyd; Nathanson, Carol (1988).The Constellations: An Enthusiast's Guide To The Night Sky.Doubleday. p. 39.ISBN978-0385176002.
  11. ↑Crawford, D. L.; Barnes, J. V.; Golson, J. C. (1971), "Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere",The Astronomical Journal76:1058,doi:10.1086/111220,Bibcode:1971AJ.....76.1058C
  12. ↑Garrison, R. F. (Desember 1993),"Anchor Points for the MK System of Spectral Classification",Bulletin of the American Astronomical Society25:1319,Bibcode:1993AAS...183.1710G,archived fromthe originalon 2019-06-25,https://web.archive.org/web/20190625094716/http://www.astro.utoronto.ca/~garrison/mkstds.html,besoek op 2012-02-04
  13. ↑"The Colour of Stars",Australia Telescope, Outreach and Education(Commonwealth Scientific and Industrial Research Organisation), 21 Desember 2004, archived fromthe originalon 2012-03-10,https://www.webcitation.org/6630AbtJZ?url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html,besoek op 2012-01-16
  14. ↑Cassinelli, J. P.et al.(Februarie 1994), "X-ray emission from near-main-sequence B stars",Astrophysical Journal, Part 1421(2): 705–717,doi:10.1086/173683,Bibcode:1994ApJ...421..705C
  15. ↑Bopp, B. W; Caplinger, J. R; Crosby, N. A; Mahoney, D. F; O'Brien, S. P; Dempsey, R. C (1989). "Is the MK Standard eta UMa an Incipient be Star?".Information Bulletin on Variable Stars.3347:1.Bibcode:1989IBVS.3347....1B.
  16. ↑"Bulletin of the IAU Working Group on Star Names, No. 1"(PDF).Besoek op28 Julie2016.

Eksterne skakels

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