Cyg X3 X-ray Halo

A Halo of X-rays

Surrounding every object in the heavens is a halo of radiation. This halo has a rather prosaic cause - it's produced by the dust which permeates the Galaxy. The image above shows probably the best example of an X-ray halo yet obtained. This halo surrounds the weird binary system Cygnus X-3, 2 gravitationally bound stars, one which is probably a compact object like a neutron star, and one which is probably a star on its way to becoming a neutron star. Material from the companion falls on the neutron star and produces X-rays. If space were truly empty this object would appear as an unresolvable point of light. In reality, dust in the Galaxy between us and Cygnus X-3 scatters the X-radiation from the star, so the point of light appears larger than it really is. This mechanism is similar to the way ice crystals in our atmosphere produce halos around the sun (though such solar halos are the result of the bending, not the scattering, of light). The false-color image above shows the X-ray halo around Cyg X-3 as a blue glow around the central (yellow-red) source. This image was obtained by the ACIS instrument on the Chandra X-ray observatory. Since Cyg X-3 varies, astronomers can use the delay in the variability in the scattered "dust halo" to measure an accurate distance to the star.

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Each week the HEASARC brings you new, exciting and beautiful images from X-ray and Gamma ray astronomy. Check back each week and be sure to check out the HEAPOW archive!

Page Author: Dr. Michael F. Corcoran
Last modified May 1, 2000