Sirius is the brightest star...Polaris is bigger then Sirius, Polaris is 360 to 820 light years away from earth, and Sirius is only 8.6 light years away. The Sirius star is known as the dog constalation, The polaris star is found at the tip and corner of the big dipper and the little dipper
Sirius is a binary star system Sirius A and Sirius B.The distance separating Sirius A from B varies between 8.1 and 31.5 AU. (See related question).
No. There is no such thing a a cold star. Sirius consists of two stars, both of which are hotter than the average star.
Sirius is a star, I hope this detailed information helps.
From Wikipedia: "The age of the system [Sirius is a double star] is estimated at around 230 million years." So, a fairly young star, at least if compared to typical stars, including our own Sun.
No. Sirius is a two-star system consisting of a white main sequence star and a white dwarf.