From ScienceDaily:
Using NASA's Swift satellite, McGill University and Penn State University astronomers have identified an object that is likely one of the closest neutron stars to Earth -- and possibly the closest. The object, located in the constellation Ursa Minor, is nicknamed Calvera, If confirmed, it would be only the eighth known "isolated neutron star" -- meaning a neutron star that does not have an associated supernova remnant, binary companion, or radio pulsations. What also makes this discovery unusual is that the object is not associated with any optical counterpart down to a very faint magnitude. According to Robert Rutledge of McGill University in Montreal, Quebec, (who originally called attention to the source) there are no widely accepted alternate theories for objects like Calvera that are bright in X-rays and faint in visible light. Exactly which type of neutron star it is, however, remains a mystery. As Rutledge says, "Either Calvera is an unusual example of a known type of neutron star, or it is some new type of neutron star, the first of its kind." If the observations are correct, Calvera is 250 to 1,000 light-years away and being this close close to Earth, it is a promising target for many types of research.
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