WASHINGTON, DC - SEPTEMBER 27: This Chandra X-ray image released by NASA 26 September, 2000 of the Sirius star system located 8.6 light years from Earth shows two sources and a spike-like pattern due to the support structure for the transmission grating. The bright source is Sirius B, a white dwarf star that has a surface temperature of about 25,000 degrees Celsius which produces very low energy X-rays. The dim source at the position of Sirius A - a normal star more than twice as massive as the sun - may be due to ultraviolet radiation from Sirius A leaking through the filter on the detector. The white dwarf, Sirius B, has a mass equal to the mass of the sun, packed into a diameter that is 90% that of the Earth. The gravity on the surface of Sirius B is 400,000 times that of Earth. (Photo credit should read NAS/AFP via Getty Images)
