Mizar (zvezda)
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.
  | |
| 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 |
| Oddaljenost | 82.9 ± 0.6 sv. l. (25.4 ± 0.2 pc) |
| Absolutni izsev (MV) | +0,32/+1,96[9] |
| Orbita | |
| Primarna | Mizar Aa |
| Spremljevalka | Mizar 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 | |
| Primarna | Mizar Ba |
| Spremljevalka | Mizar Bb |
| Perioda (P) | 175,55[12] |
| Glavna polos (a) | 29,849 mas |
| Izsrednost tira (e) | 0,46[12] |
| Podrobnosti | |
| Mizar Aa | |
| Masa | 2,2224±0,0221[10] M☉ |
| Polmer | 2,4 ± 0,1[11] R☉ |
| Izsev | 33,3 ± 2,1[11] L☉ |
| Temperatura | 9.000 ± 200[11] K |
| Starost | 370[13] Ma |
| Mizar Ab | |
| Masa | 2,2381±0,0219[10] M☉ |
| Polmer | 2,4 ± 0,1[11] R☉ |
| Izsev | 33,3 ± 2,1[11] L☉ |
| Temperatura | 9.000 ± 200[11] K |
| ζ2 UMa | |
| Površinska težnost (log g) | 4,40[14] cgs |
| Temperatura | 8.425[14] K |
| Tirna hitrost(v sin i) | 61[14] km/s |
| Druge oznake | |
| 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 | |
| SIMBAD | Mizar |
| 1 UMa | |
| 2 UMa | |
Za makedonsko glasbeno skupino glej Mizar (glasbena skupina).
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
- ↑ 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.
{{navedi časopis}}: Vzdrževanje CS1: samodejni prevod datuma (povezava) - ↑ Mermilliod, J.-C (1986). »Compilation of Eggen's UBV data, transformed to UBV (unpublished)«. Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ↑ 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.
- ↑ 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.
- ↑ 5,0 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.
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ 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.
- ↑ 10,0 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.
- ↑ 11,0 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.
- ↑ 12,0 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.
- ↑ 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.
- ↑ 14,0 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.
