Sirius(redirected from Alpha Canis Majoris)
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Sirius(seer -ee-ŭs, si -ree-) (Dog Star; α CMa) A white main-sequence star that is the brightest one in the constellation Canis Major and the brightest (after the Sun) and one of the nearest stars in the sky. It lies in a descending (southeasterly) line from Orion's Belt. Sirius is about 1.5 times as hot as the Sun, with a surface temperature of more than 9000 K, and is about 23 times as luminous. It is a visual binary (separation 4″.6, period 50 years), the companion, Sirius B, being the first white dwarf to be discovered. Bessel suggested (1844) that Sirius had a dark companion to account for the star's wobbling movement. With improved telescope lenses Alvan G. Clark detected (1862) a tiny companion whose spectrum, first taken (1915) by W.S. Adams Jr., identified Sirius B as a white dwarf. The spectrum demonstrated the gravitational redshift predicted by the general theory of relativity. mv : –1.46 (A), 8.3 (B); Mv : 1.4 (A), 11.2 (B); spectral type: A1 Vm (A), DA (B); mass: 2.31 (A), 0.98 (B) times solar mass; radius: 1.7 (A), 0.022 (B) times solar radius; distance: 2.65 pc.
(α Canis Majoris), the brightest star in the heavens, with a visual stellar magnitude of — 1.46. Sirius has a luminosity 22 times greater than that of the sun; its distance from the sun is 2.7 parsecs. Sirius is a system of two stars: the satellite of Sirius, a star 10,000 times fainter than Sirius itself, was the first white dwarf to be discovered.