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Credit & Copyright: S. Lee &
D. F. Malin,
AAO
Explanation:
By chance, a collision of two galaxies has created
a surprisingly recognizable shape on a cosmic scale.
The Cartwheel Galaxy is part of a
group of galaxies
about 500 million light years away in the
constellation
Sculptor.
Two smaller galaxies in the group are visible
on the left of the
above photograph.
The Cartwheel's rim is an immense ring-like structure 100,000
light years in diameter composed of
newly formed, extremely bright, massive stars.
When galaxies collide,
they pass through each other --
their individual stars rarely come into contact.
The galaxies' gravitational fields, however, may be greatly
distorted by the collision.
In fact, the
ring-like shape
is the result of the gravitational disruption
caused by a small intruder galaxy passing
through a large one, compressing
the interstellar gas and dust, and causing a
wave of star formation wave to move out from
the impact point like a ripple across the surface of a pond.
In this case, the large galaxy may have originally been a
spiral, not unlike our own
Milky Way Galaxy,
transformed by the collision.
Recent astronomical detective work has indicated
what has become of the intruder.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: open cluster - NGC 4755
Publications with words: open cluster - NGC 4755
See also: