a couple of years ago I discovered the story online at Eldritch Dark, a CAS devoted website. http://www.eldritchdark.com/writings/short-stories/101/the-infernal-star-%28fragment%29 This dredged up another half-forgotten memory of Nemesis , the hypothetical red- or brown-dwarf star that obits our sun.  The theory is that Nemesis causes extinction events about 26 million years or so.