The stars comprising a star cluster are usually assigned the same age, since it is thought that they were all created at the same time that the cluster was formed. The motions of the blue stragglers are consistent with those of bona fide cluster members, implying that they are not interlopers or foreground objects. Several explanations have been suggested to explain the presence of blue stragglers. One thought is that they harbor asteroid-size black holes at their cores. So far, all of the profferred explanations have serious flaws.
Socket stars .
A picture book hardly seems a likely source of an astronomical discovery, especially in a world where mysteries of the universe usually tumble from sophisticated electronic instruments attached to huge telescopes. High-resolution photographs of nebulae show large numbers of faint stars surrounded by circular or oval 'empty' regions, giving the impression that the stars are sitting in 'sockets,' a few arc seconds across, swept free of nebulosity. Feibelman rules out photographic effects, such as halation, but has no ready explanation for socket stars. He considers this strong evidence that socket stars are surrounded by shells of dust and may represent an unrecognized stage of stellar evolution. William R. Corliss Other Sites of Interest SIS .