WIYN (3.5m telescope) image
|Here is an example of a chance alignment whose probability boggles
the mind. However, in a Universe the size of our own even the seemingly
impossible happens every so often. In the foreground is a small barred
spiral galaxy- PGC 69457. Given a value of Hubble's constant of 75- this
galaxy is roughly 500 million light years away. Think that is incredible?
Look closely at the nucleus of this galaxy, it appears to have four parts!
While questionably resolved in this amateur image the WIYN image (below) and
HST images of the same clearly show this strange feature. The four images
are not of the nucleus of PGC 69457, instead they are images of a background
quasar! (QSO2237+0305). This quasar (very luminous galaxy of the early
Universe) is around 13 billion light years away! The mass of PGC 69457
changes the geometry (curvature) of space. As the light of the quasar
passes near to the foreground galaxy, it acts like a lens and shows us multiple
images of the background quasar. This is one of the best examples of the effect
that Einstein postulated in the early 1900's (and much later detected in this
example in 1989 (Huchra et al). More recently astronomers have discovered that
the four images change in their relative brightness due to stars in the
foreground galaxy. By measuring the difference of time of these variations
astronomers can learn alot about both objects.
|L R G B color production was used to create this image.||
Minimum credit line: Adam Block/NOAO/AURA/NSF
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