Mu Cassiopeiae

A close binary system located almost 25 light years out.  Star A is a G5VI sub-dwarf, about 10 billion years old and low on metals, indicating it’s likely Population II.  Star B is a red dwarf that approaches A as closely as 3.3 AU -- too close to allow an Earthlike planet, even if age and metallicity didn’t already make this system a poor prospect.

ETA: Mamajek and Hildebrand give an age range of only 5.3 to 5.9 billion years.