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    Sirius (Alpha Canis Majoris)

    Sirius
    The brightest star in the sky and also one of the nearest to the Sun. It is nicknamed the Dog Star after its constellation of Canis Major; its proper name comes from the Greek for "searing" or "scorching." Sirius is one of the points in the Winter Triangle together with Betelgeuse in Orion and Procyon in the smaller dog, Canis Minor.

    Sirius is a binary star system. The primary (Sirius A) is a white A star. The companion (Sirius B, or "the Pup"), orbits with a period of 49.97 years, and was the first white dwarf to be discovered. Following Bessel's suggestion (1844) that Sirius had a dark companion to account for the star's wobbling movement, this object was optically identified by Alvan G. Clark in 1862. Spectroscopic measurements of Sirius B, by Walter S. Adams, Jr. in 1925, revealed its true nature.1 With a diameter of 12,000 km, Sirius B is roughly the same size as the Earth but has about the same mass as the Sun. It is so densely packed that an average person standing on its surface would weigh the equivalent of 23,000 tons.


    Reference
    1. Benest, D. "Planetary Orbits in the Elliptic Restricted Problem. II - The Sirius System," Astronomy & Astrophysics, 223, 361 (1989).

    artowork of Sirius A and B
    Artist's impression of Sirius A (left) and Sirius B. Credit: NASA
      A B
    spectral type A1V wdA5
    apparent magnitude -1.44 8.60
    absolute magnitude 1.45 11.33
    luminosity (Sun = 1) 26 0.002
    surface temperature 9,900 K 25,200 K
    mass (Sun = 1) 2.14 0.98
    radius (Sun = 1) 1.7 0.008
    distance 8.60 light-years (2.63 pc) same
    position R.A. 06h 45m 8.92s,
    Dec. -16° 42' 58.02"    		 same


    Related entries

       • nearest stars
       • brightest stars
       • Sirius, mystery of red color


    Related category

       • NOTABLE STARS



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