Eltanin

Eltanin |

Eltanin se ligging (in die rooi sirkel).
Sterrebeeld | Draak
Bayer-naam | Gamma Draconis
Spektraaltipe | K5 III[1]
Soort | Reusester
Waarnemingsdata (Epog J2000)
Regte klimming | 17h 56m 36.36988s[2]
Deklinasie | +51° 29′ 20.0242″[2]
Skynmagnitude (m) | 2,23[3]
Absolute magnitude (M) | -1,93 ± 0,07[4]
B-V-kleurindeks  | +1,53[3]
U-B-kleurindeks  | +1,87[3]
Besonderhede
Massa (M☉) | 1,72[5]
Radius (R☉) | 48,15 ± 1,09[4]
Ligsterkte (L☉) | 471 ± 30[4]
Temperatuur (K) | 3 930[4]
Rotasiespoed (km/s) | 6[6]
Metaalinhoud [Fe/H] | -0,14[7]
Ander name
Etamin, Ettanin, Rastaban, Rasaben, Gamma Draconis, 33 Draconis, BD +51°2282, FK5 676, HD 164058, HIP 87833, HR 6705, SAO 30653
| Portaal    | Sterrekunde

|

Eltanin (ook bekend as Gamma Draconis en γ Dra) is ’n ster in die noordelike sterrebeeld Draak (Draco). Dit is die helderste ster in die sterrebeeld, met ’n skynbare magnitude van 2,4.[2]

Eltanin is 154,3 ligjare van die Son af.[2][8][9] In 1728, terwyl James Bradley onsuksesvol probeer het om die ster se parallaks te meet, het hy die afwyking van lig ontdek wat deur die Aarde se beweging veroorsaak is. Dié ontdekking het Copernicus se teorie bevestig dat die Aarde om die Son draai.[10]

Oor 1,5 miloen jaar sal Eltanin sowat 28 ligjare van die Aarde af wees. As sy absolute magnitude nie verander nie, sal dit ’n ruk lank die helderste ster aan die naghemel wees, amper so helder soos Sirius tans is.[10]

## Eienskappe

[wysig | wysig bron]

Eltanin is ’n geëvolueerde reusester met ’n oranje kleur[11] en ’n sterreklassifikasie van K5 III.[1] Sy spektrum dien sedert 1943 as een van die stabiele ankerpunte waarvolgens ander sterre geklassifiseer word.[12] Sy massa is 72%[5] groter as die Son s’n en dit het uitgesit tot ’n radius van 48 keer dié van die Son.[4] Sy ligsterkte is omtrent 471 keer[4] die Son s’n, al is dit met sy oppervlaktemperatuur van 3 930 K[4] koeler as die Son

## Name

[wysig | wysig bron]

Die ster se Bayer-naam is "Gamma Draconis" en sy Flamsteed-naam "33 Draconis". Dit het die tradisionele naam "Eltanin" (of "Etamin" of "Ettanin"),[13][14] wat afgelei is van die Arabiese التنين At-Tinnin "Die Groot Slang". Die Internasionale Astronomiese Unie se sternaamwerkgroep (WGSN) het dié naam vir die ster op 21 Augustus 2016 goedgekeur.[15]

## Verwysings

[wysig | wysig bron]

1. ↑ 1,0 1,1 Morgan, W. W.; Keenan, P. C. (1973), "Spectral Classification", Annual Review of Astronomy and Astrophysics 11 (1): 29, doi:10.1146/annurev.aa.11.090173.000333, Bibcode: 1973ARA&A..11...29M
2. ↑ 2,0 2,1 2,2 2,3 van Leeuwen, F (November 2007). "Hipparcos, the New Reduction". Astronomy and Astrophysics. 474 (2). VizieR; Centre de Données astronomiques de Strasbourg: 653–664\. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Besoek op 21 November 2010.653-664&rft.date=2007-11&rft_id=info:arxiv/0708.1752&rft_id=info:doi/10.1051/0004-6361:20078357&rft_id=info:bibcode/2007A&A...474..653V;&rft.aulast=van+Leeuwen&rft.aufirst=F&rft_id=http://vizier.u-strasbg.fr/viz-bin/VizieR-S?HIP%2087833&rfr_id=info:sid/af.wikipedia.org:Eltanin" class="Z3988">
3. ↑ 3,0 3,1 3,2 Oja, T. (Augustus 1991). "UBV photometry of stars whose positions are accurately known. VI". Astronomy and Astrophysics Supplement Series. 89 (2): 415–419\. Bibcode:1991A&AS...89..415O.415-419&rft.date=1991-08&rft_id=info:bibcode/1991A&AS...89..415O;&rft.aulast=Oja&rft.aufirst=T.&rfr_id=info:sid/af.wikipedia.org:Eltanin" class="Z3988">`{{cite journal}}`: CS1 maint: postscript (link)
4. ↑ 4,0 4,1 4,2 4,3 4,4 4,5 4,6 Piau, L. et al. (Februarie 2011), "Surface convection and red-giant radius measurements", Astronomy and Astrophysics 526: A100, doi:10.1051/0004-6361/201014442, Bibcode: 2011A&A...526A.100P
5. ↑ 5,0 5,1 Dehaes, S. et al. (September 2011), "Structure of the outer layers of cool standard stars", Astronomy & Astrophysics 533: A107, doi:10.1051/0004-6361/200912442, Bibcode: 2011A&A...533A.107D
6. ↑ Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M
7. ↑ McWilliam, Andrew (Desember 1990). "High-resolution spectroscopic survey of 671 GK giants". Astrophysical Journal Supplement Series (PDF). 74: 1075–1128\. Bibcode:1990ApJS...74.1075M. doi:10.1086/191527.1075-1128&rft.date=1990-12&rft_id=info:doi/10.1086/191527&rft_id=info:bibcode/1990ApJS...74.1075M&rft.aulast=McWilliam&rft.aufirst=Andrew&rfr_id=info:sid/af.wikipedia.org:Eltanin" class="Z3988">
8. ↑ Perryman, M. A. C.; Lindegren, L.; Kovalevsky, J. (Julie 1997), "The Hipparcos Catalogue", Astronomy and Astrophysics 323: L49–L52, Bibcode: 1997A&A...323L..49P
9. ↑ Perryman, Michael (2010), "The Making of History's Greatest Star Map", The Making of History's Greatest Star Map:, Astronomers’ Universe (Heidelberg: Springer-Verlag), doi:10.1007/978-3-642-11602-5, ISBN 978-3-642-11601-8, Bibcode: 2010mhgs.book.....P
10. ↑ 10,0 10,1 Kaler, James B. "ELTANIN (Gamma Draconis)". Stars (in Engels). University of Illinois. Geargiveer vanaf die oorspronklike op 13 Desember 2019. Besoek op 21 November 2010.
11. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, archived from the original on 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
12. ↑ Garrison, R. F. (Desember 1993), "Anchor Points for the MK System of Spectral Classification", Bulletin of the American Astronomical Society 25: 1319, Bibcode: 1993AAS...183.1710G, archived from the original on 2019-06-25, https://web.archive.org/web/20190625094716/http://www.astro.utoronto.ca/~garrison/mkstds.html, besoek op 2012-02-04
13. ↑ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2de hersiene uitg.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
14. ↑ "IAU Catalog of Star Names" (in Engels). Geargiveer vanaf die oorspronklike op 29 Mei 2020. Besoek op 28 Julie 2016.
15. ↑ IAU Working Group on Star Names (WGSN), International Astronomical Union, archived from the original on 21 Maart 2020, https://web.archive.org/web/20200321195254/https://www.iau.org/science/scientific_bodies/working_groups/280/, besoek op 22 Mei 2016.

## Eksterne skakels

[wysig | wysig bron]

* Hierdie artikel is vertaal uit die Engelse Wikipedia