star in constellation of Ursa Major

Merak or Beta Ursae Majoris is a star in the constellation Ursa Major. It is a white star three times larger than our Sun.

Beta Ursae Majoris
Merak is located in 100x100

Merak in Ursa Major
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension  11h 01m 50.47654s[1]
Declination +56° 22′ 56.7339″[1]
Apparent magnitude (V) +2.37[2]
Spectral type A1IVps[3]
U−B color index +0.00[2]
B−V color index -0.02[2]
Variable type Suspected
Radial velocity (Rv)-12.0[4] km/s
Proper motion (μ) RA: +81.43[1] mas/yr
Dec.: +33.49[1] mas/yr
Parallax (π)40.90 ± 0.16[1] mas
Distance79.7 ± 0.3 ly
(24.45 ± 0.10 pc)
Absolute magnitude (MV)+0.61[5]
Mass2.7[6] M
Radius3.021 ± 0.038[7] R
Luminosity63.015 ± 1.307[7] L
Surface gravity (log g)3.83[8] cgs
Temperature9377 ± 75[7] K
Rotational velocity (v sin i)46[9] km/s
Age500 ± 100[8] Myr
Other designations
Merak, Mirak,[10] β Ursae Majoris, β UMa, Beta UMa, 48 Ursae Majoris, BD+57°1302, FK5 416, GC 15145, HD 95418, HIP 53910, HR 4295, PPM 32912, SAO 27876[11]
Database references

Related pagesEdit


  1. 1.0 1.1 1.2 1.3 1.4 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. S2CID 18759600.
  2. 2.0 2.1 2.2 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
  3. Phillips, N. M.; Greaves, J. S.; Dent, W. R. F.; Matthews, B. C.; Holland, W. S.; Wyatt, M. C.; Sibthorpe, B. (2010). "Target selection for the SUNS and DEBRIS surveys for debris discs in the solar neighbourhood". Monthly Notices of the Royal Astronomical Society. 403 (3): 1089. arXiv:0911.3426. Bibcode:2010MNRAS.403.1089P. doi:10.1111/j.1365-2966.2009.15641.x. S2CID 119262858.
  4. Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. Determination of Radial Velocities and Their Applications. Vol. 30. University of Toronto: International Astronomical Union. p. 57. Bibcode:1967IAUS...30...57E.
  5. Eggen, Olin J. (August 1998), "The Sirius Supercluster and Missing Mass near the Sun", The Astronomical Journal, 116 (2): 782–788, Bibcode:1998AJ....116..782E, doi:10.1086/300465.
  6. Wyatt, M. C.; et al. (July 2007), "Steady State Evolution of Debris Disks around A Stars", The Astrophysical Journal, 663 (1): 365–382, arXiv:astro-ph/0703608, Bibcode:2007ApJ...663..365W, doi:10.1086/518404, S2CID 18883195
  7. 7.0 7.1 7.2 Boyajian, Tabetha S.; et al. (February 2012), "Stellar Diameters and Temperatures. I. Main-sequence A, F, and G Stars", The Astrophysical Journal, 746 (1): 101, arXiv:1112.3316, Bibcode:2012ApJ...746..101B, doi:10.1088/0004-637X/746/1/101, S2CID 18993744. See Table 10.
  8. 8.0 8.1 Monier, R. (November 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
  9. Royer, F.; Zorec, J.; Gómez, A. E. (February 2007), "Rotational velocities of A-type stars. III. Velocity distributions", Astronomy and Astrophysics, 463 (2): 671–682, arXiv:astro-ph/0610785, Bibcode:2007A&A...463..671R, doi:10.1051/0004-6361:20065224, S2CID 18475298
  10. Allen, Richard Hinckley (1899), "Star-names and their meanings", New York, G. E. Stechert: 438,
  11. "MERAK -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-01