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Astronomy Picture of the Day
The Einstein Cross Gravitational Lens
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zorg.ch
#70763
by
[z]Barbara Harris
@
28.03.2005 00:00
- nach oben -
The Einstein Cross Gravitational Lens
Explanation:
Most galaxies have a single nucleus -- does this galaxy have four?
The strange answer leads
astronomers
to conclude that the nucleus of the surrounding
galaxy is not even visible in
this image
.
The central
cloverleaf
is rather light emitted from a background
quasar
.
The gravitational field of the visible foreground
galaxy breaks light from this distant
quasar
into four distinct images.
The
quasar
must be
properly aligned behind the center
of a massive galaxy for a
mirage like this
to be evident.
The general effect is known as
gravitational lensing
, and this specific case is known as the
Einstein Cross
.
Stranger still, the images of the
Einstein Cross
vary in relative brightness,
enhanced occasionally by the additional
gravitational microlensing
effect of specific stars in the foreground galaxy.
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