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
CXC operated for
NASA by the Smithsonian Astrophysical