The discovery of RX J0720.4-3125 and its pulse period of 8.391 s indicates that we found an isolated neutron star which probably accretes matter from the ambient interstellar medium. A possible scenario including common envelope evolution of a high mass X-ray binary is consistent with the required low space velocity, the low distance to the galactic plane and the low magnetic field strength of less than 1010 G and could mean that isolated neutron stars have larger velocities and are more difficult to detect in the ROSAT all-sky survey than expected. The negative results for identifications of old isolated neutron stars in sample areas from the ROSAT all-sky support this picture.
© European Southern Observatory (ESO) 1997
Online publication: October 15, 1997