The most appropriate title would be " New Planet Discovered in Binary Star System ".
This title doesn't have enough glitz and glamour to be the headline of the same information in a newspaper ... as they say, it wouldn't "sell papers". So a headline writer would have to make up a gripping, understandable, grabbing, popular, slightly misleading headline for it.
But the kind of people who read Nature don't need to be baited or tricked into reading something. They're already interested in the subject, and they may be people who work in researching it. They read that journal to keep up with what's happening with things they're already interested in.
Remember ... part of the modern Scientific Method is to let other scientists know all about what you're doing and what you're finding. Nature is one of the places where real scientists do that.
