Alkor

Iz Wikipedije, proste enciklopedije
(Preusmerjeno s strani 80 ursae majoris)
Alkor
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. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.{{navedi časopis}}: Vzdrževanje CS1: samodejni prevod datuma (povezava)
  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. arXiv:0911.5028. Bibcode:2010AJ....139..919M. 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. arXiv:0912.1597. Bibcode:2010ApJ...709..733Z. 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. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. 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. arXiv:1508.05643. Bibcode:2015ApJ...813...58J. 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. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.

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