The Hubble Space Telescope captured an image of a galaxy located approximately 320 million light-years away in the constellation of Eridanus,
the River, which is, most likely, a cosmic fossil – the aftermath of an
enormous multi-galactic pile-up, where the carnage of collision after
collision has built up a brilliant giant elliptical galaxy far outshining typical galaxies.
Scientists have found that NGC 1132 resides in an enormous halo of dark matter, comparable to the amount of dark matter usually found in an entire group of tens or hundreds of galaxies.
Galaxy NGC 1132, seen in this latest image from Hubble, belongs to a
category of galaxies called giant ellipticals. NGC 1132, together with
the small dwarf galaxies surrounding it, are dubbed a “fossil group” as
they are most likely the remains of a group of galaxies that merged
together in the recent past.
The origin of fossil group systems remains a puzzle. The most likely
explanation is that they are the end-products of a cosmic feeding frenzy
in which a large cannibal galaxy devours all of its neighbors. A less
likely explanation is that they may be very rare objects that formed in a
region or period of time where the growth of moderate-sized galaxies
was somehow suppressed, and only one large galaxy formed.
There is strong evidence that the Milky Way is
one such cannibal that has snacked on numerous smaller galaxies during
its lifetime, inheriting their stars in the process. Scientists are
keenly studying the environment surrounding galaxies such as NGC 1132
using space telescopes like Hubble, and they try to trace the history of
the formation these galaxies by analysing their properties.
In this Hubble image, NGC 1132 is seen surrounded by thousands of ancient globular clusters,
swarming around the galaxy like bees around a hive. These globular
clusters are likely to be the survivors of the disruption of their
cannibalized parent galaxies that have been eaten by NGC 1132 and may
reveal its merger history. In the background, there is a stunning
tapestry of numerous galaxies that are much further away.
Elliptical galaxies are smooth and featureless. They contain hundreds
of millions to trillions of stars, and their shapes range from nearly
spherical to very elongated in shape. Their overall yellowish color is a
telltale sign of their great age. Because elliptical galaxies do not
contain much cool gas they can no longer make new stars.
Source: The Daily Galaxy via Hubble/NASA
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