Mizar (zvezda)

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Mizar
Ursa Major constellation map.svg
Red circle.svg
Lega Mizarja (obkroženo)
Opazovalni podatki
Epoha J2000      Enakonočje J2000
Ozvezdje Veliki medved
Mizar
Rektascenzija 13h 23m 55,54048s[1]
Deklinacija +54° 55′ 31,2671″[1]
Navidezni sij (V) 2,04[2]
ζ1 UMa
Rektascenzija 13h 23m 55,543s[3]
Deklinacija +54° 55′ 31,30″[3]
Navidezni sij (V) 2,23[3]
ζ2 UMa
Rektascenzija 13h 23m 56,330s[3]
Deklinacija +54° 55′ 18,56″[3]
Navidezni sij (V) 3,88[3]
Značilnosti
ζ1 UMa
Spektralni razred A2Vp/A2Vp[4]
U−B Barvni indeks −0,01[5]
B−V Barvni indeks +0,02[5]
ζ2 UMa
Spektralni razred kA1h(eA)mA7IV-V[6]
U−B Barvni indeks +0,09[5]
B−V Barvni indeks +0,13[5]
Astrometrija
Radialna hitrost (Rv)−6,31[7] km/s
Lastno gibanje (μ)RA: 119,01[1] mas/l
Dec.: −25,97[1] mas/l
Paralaksa (π)39,36 ± 0,30[8] mas
Oddaljenost82.9 ± 0.6 sv. l.
(25.4 ± 0.2 pc)
Absolutni izsev (MV)+0,32/+1,96[9]
Orbita
PrimarnaMizar Aa
SpremljevalkaMizar Ab
Perioda (P)20,5386 days[10]
Glavna polos (a)9,83±0,03[11] mas
Izsrednost tira (e)0,5415±0,0016[10]
Naklon tira (i)60,5±0,3[10]°
Dolžina vozla (Ω)106,0±0,4[11]°
Epoha periastrona (T)RJD 54536,9904[10]
Argument periastrona (ω)
(sekundarni)
105,27±0,23[10]°
Pol-amplituda (K1)
(Argument periastrona)
66,478±0,153[10] km/s
Pol-amplituda (K2)
(sekundarni)
66,019±0,177[10] km/s
Orbita
PrimarnaMizar Ba
SpremljevalkaMizar Bb
Perioda (P)175,55[12]
Glavna polos (a)29,849 mas
Izsrednost tira (e)0,46[12]
Podrobnosti
Mizar Aa
Masa2,2224±0,0221[10] M
Polmer2,4 ± 0,1[11] R
Izsev33,3 ± 2,1[11] L
Temperatura9.000 ± 200[11] K
Starost370[13] Ma
Mizar Ab
Masa2,2381±0,0219[10] M
Polmer2,4 ± 0,1[11] R
Izsev33,3 ± 2,1[11] L
Temperatura9.000 ± 200[11] K
ζ2 UMa
Površinska težnost (log g)4,40[14] cgs
Temperatura8.425[14] K
Tirna hitrost(v sin i)61[14] km/s
Druge oznake
ζ Ursae Majoris, ζ UMa, Zeta UMa, 79 Ursae Majoris, BD+55 1598, CCDM J13240+5456, HIP 65378, WDS J13239+5456
ζ1 UMa: GC 18133, HD 116656, HR 5054, PPM 34007, SAO 28737
ζ2 UMa: GC 18134, HD 116657, HR 5055, SAO 28738
Sklici na podatkovne baze
SIMBADMizar
1 UMa
2 UMa
Lega Mizarja v ozvezdju Velikega medveda

Mízar (ζ UMa, ζ Ursae Majoris, Zeta Ursae Majoris) je zvezda v ozvezdju Velikega medveda (Ursa Major), srednja zvezda ojesa Velikega voza. Ime Mizar izvira iz arabščine ميزر mīzar in pomeni pas.

Mizar ima navidezni sij 2,40m in spektralni razred A1 V.

V bližini Mizarja se nahaja temnejša zvezda Alkor, ki ima magnitudo 4,02m. Razločevanje teh dveh zvezd z golim očesom je bil dolgo časa preskus dobrega vida. Trenutno še ni natančno znano ali zvezdi tvorita pravo dvozvezdje ali sta le navidezno tesno skupaj.

Sklici[uredi | uredi kodo]

  1. 1,0 1,1 1,2 1,3 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. Mermilliod, J.-C (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
  3. 3,0 3,1 3,2 3,3 3,4 3,5 Fabricius, C; Høg, E; Makarov, V. V; Mason, B. D; Wycoff, G. L; Urban, S. E (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384: 180–189. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822.
  4. Eggleton, P. P.; Tokovinin, A. A. (2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x.
  5. 5,0 5,1 5,2 5,3 Iriarte, Braulio; Johnson, Harold L; Mitchell, Richard I; Wisniewski, Wieslaw K (1965). "Five-Color Photometry of Bright Stars". Sky and Telescope. 30: 21. Bibcode:1965S&T....30...21I.
  6. Gray, R. O; Garrison, R. F (1987). "The early a type stars - Refined MK classification, confrontation with Stroemgren photometry, and the effects of rotation". Astrophysical Journal Supplement Series. 65: 581. Bibcode:1987ApJS...65..581G. doi:10.1086/191237.
  7. Pourbaix, D; Tokovinin, A. A; Batten, A. H; Fekel, F. C; Hartkopf, W. I; Levato, H; Morrell, N. I; Torres, G; Udry, S (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727–732. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213.
  8. Mamajek, Eric E.; Kenworthy, Matthew A.; Hinz, Philip M.; Meyer, Michael R. (2010). "Discovery of a Faint Companion to Alcor Using MMT/AO 5 μm Imaging". The Astronomical Journal. 139 (3): 919–925. arXiv:0911.5028. Bibcode:2010AJ....139..919M. doi:10.1088/0004-6256/139/3/919.
  9. King, Jeremy R; Villarreal, Adam R; Soderblom, David R; Gulliver, Austin F; Adelman, Saul J (2003). "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group". The Astronomical Journal. 125 (4): 1980. Bibcode:2003AJ....125.1980K. doi:10.1086/368241.
  10. 10,0 10,1 10,2 10,3 10,4 10,5 10,6 10,7 10,8 Behr, Bradford B; Cenko, Andrew T; Hajian, Arsen R; McMillan, Robert S; Murison, Marc; Meade, Jeff; Hindsley, Robert (2011). "Stellar Astrophysics with a Dispersed Fourier Transform Spectrograph. II. Orbits of Double-lined Spectroscopic Binaries". The Astronomical Journal. 142 (1): 6. arXiv:1104.1447. Bibcode:2011AJ....142....6B. doi:10.1088/0004-6256/142/1/6.
  11. 11,0 11,1 11,2 11,3 11,4 11,5 11,6 11,7 Hummel, C. A.; Mozurkewich, D.; Armstrong, J. T.; Hajian, Arsen R.; Elias Ii, N. M.; Hutter, D. J. (1998). "Navy Prototype Optical Interferometer Observations of the Double Stars Mizar a and Matar". The Astronomical Journal. 116 (5): 2536. Bibcode:1998AJ....116.2536H. doi:10.1086/300602.
  12. 12,0 12,1 Iliev, I. Kh; Budaj, J; Zverko, J; Barzova, I. S; Ziznovsky, J (1998). "Lithium and metal abundances in long period AM binaries". Astronomy and Astrophysics Supplement. 128 (3): 497. Bibcode:1998A&AS..128..497I. doi:10.1051/aas:1998160.
  13. Thureau, N. D; Greaves, J. S; Matthews, B. C; Kennedy, G; Phillips, N; Booth, M; Duchêne, G; Horner, J; Rodriguez, D. R; Sibthorpe, B; Wyatt, M. C (2014). "An unbiased study of debris discs around A-type stars with Herschel". Monthly Notices of the Royal Astronomical Society. 445 (3): 2558. Bibcode:2014MNRAS.445.2558T. doi:10.1093/mnras/stu1864.
  14. 14,0 14,1 14,2 Monier, R (2005). "Abundances of a sample of a and F-type dwarf members of the Ursa Major Group". Astronomy and Astrophysics. 442 (2): 563–566. Bibcode:2005A&A...442..563M. doi:10.1051/0004-6361:20053222.

Koordinati: Sky map 13h 23m 55.5s, +54° 55′ 31″