Slashdot linked up this BBCnews article detailing the first-ever measure of the mass of our closest white dwarf neighbor:

Sirius B is just 12,000km (7,500 miles) in diameter, similar to Earth, but its mass is 98% that of the Sun.

Studying Sirius B has been difficult because of the bright light coming from its neighbour, Sirius A, or the "Dog Star".

Heavy...