| 1E 1207.4-5209: A neutron star located
               about 7,000 light years from Earth. 
 
 Caption: This is an artist's
               conception of 1E 1207.4-5209, a neutron star with a polar hot
               spot and a strong magnetic field (purple lines). Chandra's
               spectrum (see box) of the hot spot of this collapsed star
               revealed two surprising dips. The graph shows the expected
               (dashed blue line) and the observed (solid green line) spectra
               of the X-radiation from the hot spot. The dips are thought to be
               absorption features caused by helium ions in the atmosphere of
               the neutron star. This interpretation implies that the strong
               gravity of the neutron star has reduced the energy of the
               photons by 17 percent.
 
 Chandra X-ray Observatory ACIS
               Image
 
 
 
                              
                  CXC operated for
                  NASA by the Smithsonian Astrophysical
                  Observatory
                |