Merak

Merak or Beta Ursae Majoris is a star in the constellation Ursa Major. It is a white star three times larger than the Sun.^[7] It is a part of an asterism called the Big Dipper.

Artist's impression of Merak when viewed close up.

Beta Ursae Majoris

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]
Characteristics
Spectral type	A1IVps[3]
U−B color index	+0.00[2]
B−V color index	-0.02[2]
Variable type	Suspected
Astrometry
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
Distance	79.7 ± 0.3 ly (24.45 ± 0.10 pc)
Absolute magnitude (MV)	+0.61[5]
Details
Mass	2.7[6] M☉
Radius	3.021 ± 0.038[7] R☉
Luminosity	63.015 ± 1.307[7] L☉
Surface gravity (log g)	3.83[8] cgs
Temperature	9377 ± 75[7] K
Rotational velocity (v sin i)	46[9] km/s
Age	500 ± 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
SIMBAD	data

Related pages

• List of brightest stars

References

1. 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. 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.{{cite journal}}: CS1 maint: unflagged free DOI (link)
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. 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. 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, Bibcode:1899sntm.book.....A
11. "MERAK -- Variable Star", SIMBAD, Centre de Données astronomiques de Strasbourg, retrieved 2012-01-01