"The Enemy Stars" by Poul Anderson published by Coronet Books, the cover illustration by Geoff Taylor was painted in April 1979.

The black star was not part of Creation. It was a fossil sun, left over from a Universe that had died before this one was born, circled by an iron tomb that had once been a planet. When the black star called, four men went to the galaxy's edge. Only one came back. But he did not come back alone . . .
 
Poul Anderson was born in 1926 in Pennsylvania and educated at the University of Minnesota where he gained a degree in physics in 1948. Among his many fine novels are Brain Wave, The Avatar, War of the Wing-Men and The Boat of a Million Years.

He lived in Orinda, California, where he died in 2001.