A model of
AC211
AC 211 is considered to be an
eclipsing, or near-eclipsing binary with an inclination >80°. The accretion
disc has considerable vertical structure, probably in the form of a rim
aropund the outer edge. The height of this wall varies with position around
the disc, being highest at the point where the accretion stream strikes
the disc edge. The thickness of the disc and the high inclination of AC211
effectively obscured the compact object from us. The X-rays we detect are
therefore from an 'accretion disc corona' which surrounds the compact object,
but which is sufficiently large to be visible from Earth despite the disc
structure. The relative sizes of the disc structure, accretion disc and
accretion disc corona are uncertain, but the figure illustrates how the
blueshifted (left-hand) side of the corona is obscured more than the red.
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