Objects and Accretion

Isolated neutron stars and white dwarfs are initially formed with surface temperatures representative of the temperature of the core of the progenitor star, T lO -lO K, and as such should be sources of thermal blackbody X-ray emission, though the spectrum may be modified by the residual atmosphere of the compact object. Detection of this emission is difficult since the compact object cools quickly to temperatures too low to produce X-rays. The pointlike object at the center of the Chandra X-ray image of the supernova remnant Cas A shown in F i g. 5 may represent a young, hot isolated neutron star, though the emission appears too faint to be produced over the entire surface of a 10-km-radius neutron star and may rather represent emission from a small hot region on the neutron star surface. 

FIGURE 5 Chandra X-ray Observatory image of the Cas A supernova remnant. The point source at the center of the image is beiieved to be either a neutron star or biack hoie produced by the supernova expiosion. [Credit NASA/CXC/SAO.] 

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