Cebalrai

Cebalrai
	Cebalrai se ligging (in die rooi sirkel).
Sterrebeeld	Slangdraer
Bayer-naam	Beta Ophiuchi
Spektraaltipe	K2 III
Soort	Reusester
	Waarnemingsdata (Epog J2000)
Regte klimming	17h 43m 28.35265s
Deklinasie	+04° 34′ 02.2955″
Skynmagnitude (m)	2,749 (2,75 tot 2,77)
Absolute magnitude (M)	+0,77 ± 0,04
B-V-kleurindeks	+1,170
U-B-kleurindeks	+1,253
	Besonderhede
Massa (M☉)	1,13
Radius (R☉)	12,42 ± 0,13
Ligsterkte (L☉)	63,4 ± 3,2
Ouderdom (jaar)	3,82 ± 1,86 miljard
Temperatuur (K)	4 467
Afstand (ligjaar)	81,8
Rotasiespoed (km/s)	5,4
Metaalinhoud [Fe/H]	0,04
	Eienskappe
Veranderlikheid	K-tipe reus,
Planete	Dalk 1
	Ander name
	Cebalrai, Celbalrai, Cheleb, Kelb Alrai, 60 Oph, 60 Ophiuchi, BD +04°3489, FK5 665, HD 161096, HIP 86742, HR 6603, SAO 122671.
Portaal	Sterrekunde

Cebalrai (ook bekend as Beta Ophiuchi of β Oph) is ’n ster in die sterrebeeld Slangdraer (Ophiuchus). Sy skynbare magnitude is 2,7^[3] en dit is dus redelik maklik met die blote oog sigbaar, selfs in stedelike gebiede. Volgens parallaksmetings is die ster sowat 81,8 ligjare van die Son af.^[2]

Eienskappe

Cebalrai is ’n reusester met ’n sterreklassifikasie van K2 III.^[1] Hoewel sy massa net 13% groter as dié van die Son is,^[5] is dit in ’n stadium van sy evolusie waar die atmosfeer tot 12 keer die grootte van die Son s’n uitgesit het en sy ligsterkte tot 63 keer dié van die Son.^[6] Sy oppervlaktemperatuur is redelik koel, sowat 4 467 K,^[5] wat dit die oranje kleur van ’n K-tipe ster gee.^[12] Nes by sommige ander K-tipe reuse wissel Cebalrai se helderheid effens, met sowat 0,02 magnitude.^[8]^,^[9]

Die ster is lid van die Melkweg se dunskyfsterre; dit is in ’n wentelbaan met ’n lae eksentrisiteit wat dit neem van 27 300 tot 30 900 ligjare van die galaktiese sentrum af, en van 620 ligjare bo tot dieselfde afstand onder die galaktiese vlak.^[1]

Moontlike planeetstelsel

Wisselings in sy radiale snelheid, met ’n tydperk van 142 dae, dui op die moontlikheid van ’n eksoplaneet wat om Cebalrai wentel. Tot dusver is geen planeet ontdek nie; periodieke radiale pulserings wat deur intrinsieke sterveranderlikheid veroorsaak word, kan die rede vir die waargenome wisselings wees.^[9]

Die Cebalrai-stelsel
Planeet of skyf (vanaf ster)	Massa	Halwe lengteas (AE)	Wentelperiode (dae)	Eksentrisiteit	Baanhelling (°)	Radius
b (onbevestig)	≥317 M_⊕	≥ 0,6	142,3	—	—	—

Name

Die ster se Bayer-naam is "Beta Ophiuchi" en sy Flamsteed-naam "60 Ophiuchi". Die tradisionele naam, "Cebalrai", kom van die Arabiese كلب الراعي kalb al-rā‘ī, "die veewagter se hond".^[13].

In 2016 het die Internasionale Astronomiese Unie se sternaamwerkgroep (WGSN) die naam "Cebalrai" vir die ster goedgekeur.^[14]

Verwysings

↑ ^1,0 ^1,1 ^1,2 ^1,3 ^1,4 Soubiran, C. et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91–101, doi:10.1051/0004-6361:20078788, Bibcode: 2008A&A...480...91S
↑ ^2,0 ^2,1 ^2,2 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V
↑ ^3,0 ^3,1 ^3,2 ^3,3 Oja, T., "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series 65 (2): 405–4
↑ Carney, Bruce W. et al. (March 2008), "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars", The Astronomical Journal 135 (3): 892–906, doi:10.1088/0004-6256/135/3/892, Bibcode: 2008AJ....135..892C
↑ ^5,0 ^5,1 ^5,2 ^5,3 Allende Prieto, C.; Lambert, D. L. (1999), "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures", Astronomy and Astrophysics 352: 555–562, Bibcode: 1999A&A...352..555A
↑ ^6,0 ^6,1 ^6,2 Berio, P. et al. (November 2011), "Chromosphere of K giant stars. Geometrical extent and spatial structure detection", Astronomy & Astrophysics 535: A59, doi:10.1051/0004-6361/201117479, Bibcode: 2011A&A...535A..59B
↑ 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
↑ ^8,0 ^8,1 Edmonds, Peter D.; Gilliland, Roland L. (June 1996), "K Giants in 47 Tucanae: Detection of a New Class of Variable Stars", Astrophysical Journal Letters 464: L157–L160, doi:10.1086/310108, Bibcode: 1996ApJ...464L.157E
↑ ^9,0 ^9,1 ^9,2 Hatzes, Artie P.; Cochran, William D. (September 1996), "The Radial Velocity Variability of the K Giant beta Ophiuchi. II. Long-Period Variations", Astrophysical Journal 468: 391–397, doi:10.1086/177699, Bibcode: 1996ApJ...468..391H
↑ Allen, Richard Hinckley (1899), Star-names and their meanings, G. E. Stechert, p. 301, https://books.google.com/books?id=5xQuAAAAIAAJ&pg=PA301
↑ "rho Per -- Semi-regular pulsating Star", SIMBAD (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Beta+Ophiuchi, besoek op 2012-01-29
↑ "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
↑ Book Of Fixed Stars, Al-Sufi, Bodleian Ms., https://digital.bodleian.ox.ac.uk/inquire/Discover/Search/#/?p=c+0,t+,rsrs+0,rsps+10,fa+,so+ox%3Asort%5Easc,scids+,pid+c1caa84c-f6d2-483f-9eb4-2439cccdc801,vi+62392615-fb52-4c0c-bf97-ed5153a1d509
↑ "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Besoek op 28 Julie 2016.

Eksterne skakels

Cebalrai op WikiSky: DSS2, SDSS, GALEX, IRAS, Hydrogen α, X-Ray, Astrophoto, Sky Map, Artikels en foto's
Hierdie artikel is vertaal uit die Engelse Wikipedia

[aaa480_1_91-1] 1,0 ^1,1 ^1,2 ^1,3 ^1,4 Soubiran, C. et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91–101, doi:10.1051/0004-6361:20078788, Bibcode: 2008A&A...480...91S

[aaa474_2_653-2] 2,0 ^2,1 ^2,2 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V

[aaass65_2_405-3] 3,0 ^3,1 ^3,2 ^3,3 Oja, T., "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series 65 (2): 405–4

[aj135_3_892-4] Carney, Bruce W. et al. (March 2008), "Rotation and Macroturbulence in Metal-Poor Field Red Giant and Red Horizontal Branch Stars", The Astronomical Journal 135 (3): 892–906, doi:10.1088/0004-6256/135/3/892, Bibcode: 2008AJ....135..892C

[aaa352_555-5] 5,0 ^5,1 ^5,2 ^5,3 Allende Prieto, C.; Lambert, D. L. (1999), "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures", Astronomy and Astrophysics 352: 555–562, Bibcode: 1999A&A...352..555A

[aaa535_A59-6] 6,0 ^6,1 ^6,2 Berio, P. et al. (November 2011), "Chromosphere of K giant stars. Geometrical extent and spatial structure detection", Astronomy & Astrophysics 535: A59, doi:10.1051/0004-6361/201117479, Bibcode: 2011A&A...535A..59B

[aj135_1_209-7] 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

[apjl464_L157-8] 8,0 ^8,1 Edmonds, Peter D.; Gilliland, Roland L. (June 1996), "K Giants in 47 Tucanae: Detection of a New Class of Variable Stars", Astrophysical Journal Letters 464: L157–L160, doi:10.1086/310108, Bibcode: 1996ApJ...464L.157E

[apj468_391-9] 9,0 ^9,1 ^9,2 Hatzes, Artie P.; Cochran, William D. (September 1996), "The Radial Velocity Variability of the K Giant beta Ophiuchi. II. Long-Period Variations", Astrophysical Journal 468: 391–397, doi:10.1086/177699, Bibcode: 1996ApJ...468..391H

[allen1899-10] Allen, Richard Hinckley (1899), Star-names and their meanings, G. E. Stechert, p. 301, https://books.google.com/books?id=5xQuAAAAIAAJ&pg=PA301

[SIMBAD-11] "rho Per -- Semi-regular pulsating Star", SIMBAD (Centre de Données astronomiques de Strasbourg), http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Beta+Ophiuchi, besoek op 2012-01-29

[csiro-12] "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

[13] Book Of Fixed Stars, Al-Sufi, Bodleian Ms., https://digital.bodleian.ox.ac.uk/inquire/Discover/Search/#/?p=c+0,t+,rsrs+0,rsps+10,fa+,so+ox%3Asort%5Easc,scids+,pid+c1caa84c-f6d2-483f-9eb4-2439cccdc801,vi+62392615-fb52-4c0c-bf97-ed5153a1d509

[WGSN1-14] "Bulletin of the IAU Working Group on Star Names, No. 1" (PDF). Besoek op 28 Julie 2016.

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