(See description below)
Hercules Cluster of Galaxies
These
are galaxies of the Hercules Cluster, an archipelago of island
universes a mere 500 million light-years away. Also known as Abell
2151, this cluster is loaded with gas and dust rich, star-forming
spiral galaxies but has relatively few elliptical galaxies, which lack
gas and dust and the associated newborn stars. The colors in this
remarkably deep composite image clearly show the star forming galaxies
with a blue tint and galaxies with older stellar populations with a
yellowish cast. The sharp picture spans about 3/4 degree across the
cluster center, corresponding to over 6 million light-years at the
cluster's estimated distance. Diffraction spikes around stars indicate
foreground stars in our own Milky Way galaxy. In this cosmic vista,
many galaxies seem to be colliding or merging, while others seem
distorted—clear evidence that cluster galaxies commonly interact. In
fact, the Hercules Cluster itself may be seen as the result of ongoing
mergers of smaller galaxy clusters and is thought to be similar to
young galaxy clusters in early Universe.
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