Delta Ursae Majoris has 63% more mass than the Sun[6] and is about 1.4 times its radius.[7] It has a
stellar classification of A3 V,[3] which means it is an
A-type main sequence star that is generating energy at its core through the
nuclear fusion of hydrogen. It shines at 14[7] times the luminosity of the Sun, with this energy being emitted from its outer envelope at an
effective temperature of 9,480 K.[7] This gives it the white hue typical of an A-type star.[13]
It bore the traditional name Megrez/ˈmɛɡrɛz/ and the historical name Kaffa. Megrez comes from the
Arabic: المغرزal-maghriz 'the base [of the bear's tail]'. Professor Paul Kunitzch has been unable to find any clues as to the origin of the name Kaffa, which appeared in a 1951 publication, Atlas Coeli (
Skalnate Pleso Atlas of the Heavens) by Czech astronomer
Antonín Bečvář.[16]
In
Chinese, 北斗 (Běi Dǒu), meaning Northern Dipper, refers to an
asterism equivalent to the Big Dipper. Consequently, the
Chinese name for Delta Ursae Majoris itself is 北斗四 (Běi Dǒu sì, English: the Fourth Star of Northern Dipper) and 天權 (Tiān Quán, English: Star of Celestial Balance).[18]
^
abcdOja, T. (1986), "UBV photometry of stars whose positions are accurately known. III", Astronomy and Astrophysics Supplement Series, 65 (2): 405–4,
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1986A&AS...65..405O
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abCowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406,
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doi:
10.1086/110819
^Wielen, R.; et al. (1999), "Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions", Veröff. Astron. Rechen-Inst. Heidelb, 35 (35), Astronomisches Rechen-Institut Heidelberg: 1,
Bibcode:
1999VeARI..35....1W
^Eggen, Olin J. (August 1998), "The Sirius Supercluster and Missing Mass near the Sun", The Astronomical Journal, 116 (2): 782–788,
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1998AJ....116..782E,
doi:10.1086/300465.
^
abcdefgMalagnini, M. L.; Morossi, C. (November 1990), "Accurate absolute luminosities, effective temperatures, radii, masses and surface gravities for a selected sample of field stars", Astronomy and Astrophysics Supplement Series, 85 (3): 1015–1019,
Bibcode:
1990A&AS...85.1015M
^Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub.
ISBN978-1-931559-44-7.
^"The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from
the original on 2012-03-18, retrieved 2012-01-16
^Kunitzch, Paul; Smart, Tim (2006) [1986]. A Dictionary of Modern Star Names: A Short Guide to 254 Star Names and Their Derivations. Cambridge, Massachusetts: Sky Publishing Corporation. pp. 56, 62.
ISBN978-1-931559-44-7.