Skylook | Astronomy | Eclipses | Telescopes » Einstein http://www.skylook.net Free astronomy information including amazing pictures of the heavens, eclipses, constellations, and more. Look to the sky! Wed, 08 Feb 2012 02:15:04 +0000 en hourly 1 A Horseshoe Einstein Ring From Hubble http://www.skylook.net/astronomy-pictures/a-horseshoe-einstein-ring-from-hubble/ http://www.skylook.net/astronomy-pictures/a-horseshoe-einstein-ring-from-hubble/#comments Thu, 22 Dec 2011 21:59:38 +0000 Father Sky http://www.skylook.net/astronomy-pictures/a-horseshoe-einstein-ring-from-hubble/

A Horseshoe Einstein Ring from Hubble

What's large and blue and can wrap itself around an entire galaxy?

A gravitational lens mirage.

Pictured above,
the gravity of a luminous red galaxy
(LRG) has
gravitationally distorted
the light from a much more distant blue galaxy.

More typically, such light bending results in
two discernible images of the distant galaxy,
but here the
lens alignment
is so precise that the background galaxy is distorted into a horseshoe --
a nearly complete ring.

Since such a
lensing effect
was generally predicted in some detail by
Albert Einstein over
70 years ago,
rings like this are now known as
Einstein Rings.

Although LRG 3-757 was discovered in 2007 in data from the
Sloan Digital Sky Survey (SDSS),
the image shown above is a follow-up observation taken with the
Hubble Space Telescope's
Wide Field Camera 3.

Strong gravitational lenses like LRG 3-757 are more than oddities --
their multiple properties allow astronomers to determine the mass and
dark matter
content of the foreground galaxy lenses.

Read the full story:
A Horseshoe Einstein Ring from Hubble

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]]> http://www.skylook.net/astronomy-pictures/a-horseshoe-einstein-ring-from-hubble/feed/ 0 The Einstein Cross Gravitational Lens http://www.skylook.net/astronomy-pictures/the-einstein-cross-gravitational-lens/ http://www.skylook.net/astronomy-pictures/the-einstein-cross-gravitational-lens/#comments Mon, 28 Feb 2011 15:34:23 +0000 Father Sky http://skylook.net/astronomy-pictures/the-einstein-cross-gravitational-lens/

The Einstein Cross Gravitational Lens

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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