Astronomers are puzzled over an enigmatic companion to a pulsar
The mysterious entity has a mass somewhere between that of a neutron star and a black hole
![illustration of a mysterious object orbiting a pulsar](jpg/011724_am_mystery_space_object_featb14e.jpg)
An unseen object orbiting a pulsar might be an exceptionally lightweight black hole (illustrated), a very heavy neutron star, or something else entirely.
Daniëlle Futselaar/artsource.nl