Explanation:
Where do stars form when galaxies collide?
To help find out, astronomers imaged the nearby galaxy merger
NGC 2623 in high resolution with the
Hubble Space Telescope in 2007.
Analysis of this Hubble image and images of
NGC 2623 in
infrared light by the
Spitzer Space Telescope, in
X-ray light by
XMM-Newton, and in
ultraviolet light by
GALEX,
indicate that two originally
spiral galaxies appear now to be
greatly convolved and that their cores have unified into one
active galactic nucleus (AGN).
Star formation continues around this core near the
above image center, along the stretched out
tidal tails visible on either side,
and perhaps surprisingly, in an off-nuclear region on the upper left where
clusters of bright blue stars appear.
Galaxy collisions can take hundreds of millions of years and take several gravitationally destructive passes.
NGC 2623, also known as Arp 243, spans about 50,000 light years and lies about 250 million light years away toward the constellation of
the Crab (Cancer).
Reconstructing the original galaxies and how
galaxy mergers happen is often challenging,
sometimes impossible, but generally important to understanding
how our universe evolved.
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