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Canis Major constellation
A simulated image of Sirius A and B using Celestia

Sirius is the brightest star in the night sky. It is a binary star system in Canis Major, near Orion. It has an apparent magnitude of −1.46. The system is between 200 and 300 million years old.[1] It was originally composed of two bright bluish stars.

The Egyptians called this star Sopdet. They relied on this star to predict when the flood season would start.

Sirius is sometimes called the Dog Star. The phrase the dog days of summer means the hottest days of summer. Some of the ancient peoples thought that the heat from Sirius added to the heat of the Sun.

Sirius A[change | change source]

Sirius A is about twice as massive as the Sun and has an absolute magnitude of 1.42. It is 25 times more luminous than the Sun,[1] but has a significantly lower luminosity than other bright stars such as Canopus or Rigel.

Sirius B[change | change source]

The more massive of these, Sirius B, used up its resources and became a red giant. Then it shed its outer layers and collapsed into its present state as a white dwarf, about 120 million years ago.[1]

Other pages[change | change source]

References[change | change source]

  1. 1.0 1.1 1.2 Liebert, J. et al. (2005). "The age and progenitor mass of Sirius B". The Astrophysical Journal 630 (1): L69–L72. doi:10.1086/462419.