An "Island Universe" in the Coma Cluster
A long-exposure Hubble Space Telescope image shows a
majestic face-on spiral galaxy located deep within the Coma
Cluster of galaxies, which lies 320 million light-years away in
the northern constellation Coma Berenices.
The galaxy, known as NGC 4911, contains rich lanes of dust
and gas near its center. These are silhouetted against glowing
newborn star clusters and iridescent pink clouds of hydrogen,
the existence of which indicates ongoing star formation.
Hubble has also captured the outer spiral arms of NGC 4911,
along with thousands of other galaxies of varying sizes. The
high resolution of Hubble's cameras, paired with considerably
long exposures, made it possible to observe these faint
NGC 4911 and other spirals near the center of the cluster are
being transformed by the gravitational tug of their neighbors.
In the case of NGC 4911, wispy arcs of the galaxy's outer
spiral arms are being pulled and distorted by forces from a
companion galaxy (NGC 4911A), to the upper right. The resultant
stripped material will eventually be dispersed throughout the
core of the Coma Cluster, where it will fuel the intergalactic
populations of stars and star clusters.
The Coma Cluster is home to almost 1,000 galaxies, making it
one of the densest collections of galaxies in the nearby
universe. It continues to transform galaxies at the present
epoch, due to the interactions of close-proximity galaxy systems
within the dense cluster. Vigorous star formation is triggered
in such collisions.
Galaxies in this cluster are so densely packed that they
undergo frequent interactions and collisions. When galaxies of
nearly equal masses merge, they form elliptical galaxies.
Merging is more likely to occur in the center of the cluster
where the density of galaxies is higher, giving rise to more
This natural-color Hubble image, which combines data obtained
in 2006, 2007, and 2009 from the Wide Field Planetary Camera 2
and the Advanced Camera for Surveys, required 28 hours of
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Acknowledgment: K. Cook (Lawrence Livermore National Laboratory)