↑Harry Potter Glossary at the Bloomsbury Harry Potter website: exact quote: Sirius Black's uncle who died when Sirius was seventeen, leaving him 'a decent bit of gold'. Along with the former link, In the F.A.Q. section of J.K. Rowling's Official Site, she stated that Sirius was "around twenty-two" when he was imprisoned in Azkaban. Given that he was imprisoned shortly after 31 October 1981 and attended Hogwarts from 1971 to 1978, Sirius would have been born between 1 September 1959 and 1 November 1959. This means that Alphard, who gave Sirius gold when he was 17, died between 1st September, 1977 and November 1977. Thus, Sirius, at 17, was able to buy his own place to live.