Alkor

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Alkor
Ursa Major constellation map.svg
Red circle.svg
Lega Alkorja (Mizar je obkrožen, Alkor je v tem merilu neviden)
Opazovalni podatki
Epoha J2000.0      Enakonočje J2000.0
Ozvezdje Veliki medved
Rektascenzija 13h 25m 13,53783s[1]
Deklinacija +54° 59′ 16,6548″[1]
Navidezni sij (V) +3,99[2]
Značilnosti
Spektralni razred A5Vn[3] / M3-4[4]
Astrometrija
Radialna hitrost (Rv)−9,6[5] km/s
Paralaksa (π)39,91 ± 0.13[1] mas
Oddaljenostpribl. 80 sv. l.
(pribl. 25 pc)
Absolutni izsev (MV)+2,00[2]
Podrobnosti
Alcor A
Masa1,84[6] M
Polmer1,846[7] R
Izsev14,03[6] L
Površinska težnost (log g)4,25[8] cgs
Temperatura8.221[8] K
Tirna hitrost(v sin i)228[6] km/s
Alcor B
Masa0,25[4] M
Starost0,5 ± 0,1[2] Ga
Druge oznake
g Ursae Majoris, 80 Ursae Majoris, BD+55 1603, CCDM J13240+5456D, GC 18155, HD 116842, HIP 65477, HR 5062, PPM 34021, SAO 28751, WDS J13239+5456C
Sklici na podatkovne baze
SIMBADpodatki
Alkor (levo) in Mizar

Alkor (Alcor, Saidak) je zvezda v bližini Mizarja. Imenujemo jo tudi Jahač in 80 Velikega medveda (80 UMa, 80 Ursae Majoris).

Ima navidezni sij 4,02m in sodi v spektralni razred A5 V. Spada me najbolj znane navidezne dvojne zvezde, čeprav še ni natančno znano ali res ne tvori pravega dvozvezdja z Mizarjem.

Sklici[uredi | uredi kodo]

  1. 1,0 1,1 1,2 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752. doi:10.1051/0004-6361:20078357. 
  2. 2,0 2,1 2,2 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. Bibcode:2010AJ....139..919M. arXiv:0911.5028. doi:10.1088/0004-6256/139/3/919. 
  3. Gray, R. O; Garrison, R. F (1989). "The late A-type stars - Refined MK classification, confrontation with Stromgren photometry, and the effects of rotation". Astrophysical Journal Supplement Series 70: 623. Bibcode:1989ApJS...70..623G. doi:10.1086/191349. 
  4. 4,0 4,1 Zimmerman, Neil; Oppenheimer, Ben R; Hinkley, Sasha; Brenner, Douglas; Parry, Ian R; Sivaramakrishnan, Anand; Hillenbrand, Lynne; Beichman, Charles; Crepp, Justin R; Vasisht, Gautam; Roberts, Lewis C; Burruss, Rick; King, David L; Soummer, Rémi; Dekany, Richard; Shao, Michael; Bouchez, Antonin; Roberts, Jennifer E; Hunt, Stephanie (2010). "Parallactic Motion for Companion Discovery: An M-Dwarf Orbiting Alcor". The Astrophysical Journal 709 (2): 733–740. Bibcode:2010ApJ...709..733Z. arXiv:0912.1597. doi:10.1088/0004-637X/709/2/733. 
  5. Kidger, Mark R; Martín-Luis, Fabiola (2003). "High-Precision Near-Infrared Photometry of a Large Sample of Bright Stars Visible from the Northern Hemisphere". The Astronomical Journal 125 (6): 3311. Bibcode:2003AJ....125.3311K. doi:10.1086/374996. 
  6. 6,0 6,1 6,2 Zorec, J; Royer, F (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy & Astrophysics 537: A120. Bibcode:2012A&A...537A.120Z. arXiv:1201.2052. doi:10.1051/0004-6361/201117691. 
  7. Jones, Jeremy; White, R. J; Boyajian, T; Schaefer, G; Baines, E; Ireland, M; Patience, J; Ten Brummelaar, T; McAlister, H; Ridgway, S. T; Sturmann, J; Sturmann, L; Turner, N; Farrington, C; Goldfinger, P. J (2015). "The Ages of A-Stars. I. Interferometric Observations and Age Estimates for Stars in the Ursa Major Moving Group". The Astrophysical Journal 813: 58. Bibcode:2015ApJ...813...58J. arXiv:1508.05643. doi:10.1088/0004-637X/813/1/58. 
  8. 8,0 8,1 David, Trevor J; Hillenbrand, Lynne A (2015). "The Ages of Early-type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal 804 (2): 146. Bibcode:2015ApJ...804..146D. arXiv:1501.03154. doi:10.1088/0004-637X/804/2/146. 

Koordinati: Sky map 13h 25m 13.5s, +54° 59′ 17″