THE DISCOVERY OF SIRIUS B
In modern times it was discovered that Sirius had a smaller star companion, a white dwarf, named Sirius B. Sirius B is much smaller and weaker than the brightest Sirius A. The first time Sirius B was sighted by Alvan Clarr in 1862. The star companion of Sirius is virtualy invisible, as the strongest brightnest of Sirius totally obscures it. If we subject to a x-ray examination Sirius A , we'll note that a small sized but hotther source of heat appears, it's exactly Sirius B. Sirius is a double or a multiple star (Sirius B is its companion); we can have double visual stars if the distance among the component is enough do that we can see them separated, with naked eye or with a telescope. This condition rarely happens because of enormous distance that separate our Earth from the stars. The double stars are generaly reveled by some measures of bright flow or by some spectroscopic tests. The temperature of Sirius is 9400° and such as all stars of spectral class "A", whose temperature is includied between 7500° and 11000°, has a white-blue colour. Surely Sirius isn't the brightest star, but for us it's the brightest one because of its distance from the Earth, about 8,7 light years away. Sirius is 23 times brighter than the sun, it is calculated that its diameter is 8 times bigger then the sun's diameter. The best period to see Sirius in mediterranean area is from January to March, but in February it's possible to see Sirius without any scientific instruments higher above the horizont.