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NGC 5474 is an asymmetric spiral galaxy and it it is being
dramatically disturbed by its much larger neighbor
M101. With respect to this image,
M101 is several fields away towards
the upper left direction. At first glance, it might appear that
M101 is somehow gravitationally dragging the nucleus right out
of NGC 5474. However, astronomers that model these kinds of galactic
interactions on a computer find a slightly different story. When
using tens (if not hundreds) of thousands of point masses for stars,
astronomers found that the asymmetry displayed in NGC 5474 is probably
relatively short lived. We just happen to be looking at this galaxy
in a state of "sloshed" agitation. As NGC 5474 orbits M101, the amount
of asymmetry depends of the relationship between the direction of
orbital revolution about M101 and the sense of rotation for NGC 5474's
disk. If the revolution is opposite that of disk rotation, as it is
in the case of NGC 5474, then the lopsided state can survive for
many galactic rotations after an initial (strong) tidal perturbation.
Note that the seemingly grainy appearence of this galaxy is due to partially resolving some of the brighter stars in the disk (v=20-21). A healthy sprinkling of pink starforming regions, and blue (young) stellar associations can also be seen along the spiral structure of the galaxy. |
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color production was used to create this image.
Luminance = 90 minutes
binned 1x1 |
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Minimum credit line: Adam Block/NOAO/AURA/NSF
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Updated: 5/20/2004
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