Daughter of Cygnus and Violetta (Bulstrode) Black (BFT).
Three older siblings: two brothers Pollux (1912-1990) and Marius (disowned, dates unknown), one sister Cassiopeia (1915-1992) (BFT).
Married to Charlus Potter; they had one unnamed son (BFT).
Other canon notes and references
Before it was revealed that James Potter's parents were Fleamont and Euphemia Potter, there was some speculation that he could have been Dorea and Charlus Potter's unnamed son. However, this was doubtful since Jo had told us that "James's parents were elderly, were getting on a little when he was born, which explains the only child, very pampered, had-him-late-in-life-so-he's-an-extra-treasure, as often happens, I think. They were old in wizarding terms, and they died" (TLC), and Dorea was only 57 when she died.
Possible name derivation: related to the names Dora and Dolores; Dorea is a bacterium found in human feces. Not a star or constellation.