Sirius and its companion

  • Sirius is the brightest star in the sky.

  • It is also the member of a binary star system with an orbital period of about 50 years.

  • Its companion is a white dwarf, not visible to the naked eye.

  • The wobble of Sirius caused by its orbital motion was noticed as early as 1834 by Bessel who thus suspected that it was in a binary with a period of about 50 years. The faint companion was actually discovered by Alvan Clark in 1862.

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