CK12 Earth Science

Figure 26.7: The bright star Sirius is actually a binary system with one large star (Sirius A)
and one small star (Sirius B). This image from the Hubble Space Telescope shows Sirius B
to the lower left of Sirius A. As you might guess, Sirius A is much, much brighter than Sirius
B. Sirius B once was brighter than its companion, but it became a red giant and collapsed
into its current dim state about 100-125 million years ago. ( 4 )