Alpha Circini
Alpha Circini (afgekort as α Cir) is ’n veranderlike ster in die dowwe suidelike sirkumpolêre sterrebeeld Passer (Circinus). Met ’n skynbare magnitude van 3,19[5] is dit die helderste ster in die sterrebeeld en kan dit geredelik met die blote oog gesien word. Dit is sowat 54 ligjare van die Son af.[2]
Alpha Circini
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| Die ligging van Alpha Circini (in die rooi sirkel). | ||||
| Sterrebeeld | Passer | |||
| Spektraaltipe | A7 Vp SrCrEu[1] | |||
| Soort | Hoofreeksster | |||
| Waarnemingsdata (Epog J2000) | ||||
| Regte klimming | 14h 42m 30.41958s[2] | |||
| Deklinasie | -64° 58′ 30.4934″[2] | |||
| Skynmagnitude (m) | 3,18-3,21[3] | |||
| Absolute magnitude (M) | +2,18[4] | |||
| B-V-kleurindeks | +0,24[5] | |||
| U-B-kleurindeks | +0,12[5] | |||
| Besonderhede | ||||
| Massa (M☉) | 1,5-1,7[6] | |||
| Radius (R☉) | 1,967 ± 0,066[7] | |||
| Ligsterkte (L☉) | 10,51 ± 0,60[6] | |||
| Ouderdom (jaar) | ~12 miljoen[8] | |||
| Temperatuur (K) | 7 500[6] | |||
| Rotasiespoed (km/s) | 13,0 ± 1,5[9] | |||
| Metaalinhoud [Fe/H] | 0,13[10] | |||
| Eienskappe | ||||
| Veranderlikheid | Kortperiode-Ap-veranderlike[3] | |||
| Ander name | ||||
| 17. G Circini,[11] CD−64° 86, HD 128898, HIP 71908, HR 5463, SAO 252853 | ||||
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Eienskappe
wysigDie ster behoort tot ’n klas sterre wat kortperiode-Ap-veranderlikes genoem word. Sy helderheid wissel in veelvoudige, nieradiale pulssiklusse en ’n dominante siklus van 6,8 minute.[9] Sy spektrum toon besonderse eienskappe wat veroorsaak word deur die chemiese stratifikasie van sy buitenste atmosfeer. Dit het ’n matige gebrek aan koolstof, stikstof en suurstof, terwyl dit ’n oorvloed chroom het.[6] Die sterreklassifikasie A7 Vp SrCrEu[1] dui aan dit is ’n hoofreeksster met verhoogde vlakke van stronsium, chroom en europium in sy atmosfeer (in vergelyking met ’n tipiese ster soos die Son).[12]
Alpha Circini se massa is sowat 150% tot 170% van die Son s’n[6] en sy radius is twee sonradiusse,[7] terwyl sy ligsterkte meer as 10 keer dié van die Son is. Die oppervlaktemperatuur is sowat 7 500 K en dit het dus die wit skynsel tipies van A-tipe sterre.[6][13] Dit roteer met ’n periode van 4,5 dae en die pole lê teen ’n helling van sowat 37 ± 4° met die gesigslyn van die Aarde af.[9]
Na aanleiding van sy ligging en beweging deur die ruimte is Alpha Circini ’n kandidaatlid van die Beta Pictoris-groep sterre wat ’n gemeenskaplike oorsprong het en sowat 12 miljoen jaar oud is.
Verwysings
wysig- ↑ 1,0 1,1 Gray, R. O. et al. (Julie 2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I", The Astronomical Journal 132 (1): 161–170, doi:10.1086/504637, Bibcode: 2006AJ....132..161G
- ↑ 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 Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
- ↑ Ammler-von Eiff, M.; Reiners, A. (Junie 2012), "New measurements of rotation and differential rotation in A-F stars: are there two populations of differentially rotating stars?", Astronomy & Astrophysics 542: A116, doi:10.1051/0004-6361/201118724, Bibcode: 2012A&A...542A.116A.
- ↑ 5,0 5,1 5,2 Johnson, H. L. et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory 4 (99): 99, Bibcode: 1966CoLPL...4...99J
- ↑ 6,0 6,1 6,2 6,3 6,4 6,5 Kochukhov, O.; Shulyak, D.; Ryabchikova, T. (Junie 2009), "A self-consistent empirical model atmosphere, abundance and stratification analysis of the benchmark roAp star α Circini", Astronomy and Astrophysics 499 (3): 851–863, doi:10.1051/0004-6361/200911653, Bibcode: 2009A&A...499..851K
- ↑ 7,0 7,1 Bruntt, H. et al. (Junie 2008), "The fundamental parameters of the roAp star α Circini", Monthly Notices of the Royal Astronomical Society 386 (4): 2039–2046, doi:10.1111/j.1365-2966.2008.13167.x, Bibcode: 2008MNRAS.386.2039B
- ↑ Nakajima, Tadashi; Morino, Jun-Ichi; Fukagawa, Misato (September 2010), "Potential Members of Stellar Kinematical Groups within 20 pc of the Sun", The Astronomical Journal 140 (3): 713–722, doi:10.1088/0004-6256/140/3/713, Bibcode: 2010AJ....140..713N
- ↑ 9,0 9,1 9,2 Bruntt, H. et al. (Junie 2009), "Asteroseismic analysis of the roAp star α Circini: 84d of high-precision photometry from the WIRE satellite", Monthly Notices of the Royal Astronomical Society 396 (2): 1189–1201, doi:10.1111/j.1365-2966.2009.14804.x, Bibcode: 2009MNRAS.396.1189B
- ↑ North, P.; Berthet, S.; Lanz, T. (Januarie 1994), "The nature of the F STR lambda 4077 stars. 3: Spectroscopy of the barium dwarfs and other CP stars", Astronomy and Astrophysics 281 (3): 775–796, Bibcode: 1994A&A...281..775N
- ↑ Gould, Benjamin Apthorp (1879), "Uranometria Argentina", Resultados del Observatorio Nacional Argentino en Cordoba (Buenos Aires) 1: 385, Bibcode: 1879RNAO....1.....G. See VizieR catalogue V/135A.
- ↑ Kaler, James B., "ALPHA CIR (Alpha Circini)", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/alphacir.html, besoek op 2012-01-04
- ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), 21 Desember 2004, archived from the original on 10 Maart 2012, https://www.webcitation.org/6630AbtJZ?url=http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, besoek op 2012-01-16
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