Neutron stars are tiny but extremely dense survivors of supernovae, titanic explosions that also throw out a tremendous amount of gas and dust. So it was a surprise last year when astronomers discovered Calvera, one of only seven known neutron stars unclouded by surrounding supernova debris. One possibility is Calvera somehow got flung far away from its birthplace, but for now its origins remain unknown, and astronomers are planning further observations to try to solve the mystery. This artist’s impression of the asteroid-sized Calvera was released by Pennsylvania State University 21 August; a paper will be published in The Astrophysical Journal. (Photo: Casey Reed/Penn State University)
